What is Authentication of Official Seals/Apostille?
An authentication and an apostille are both attestations from the Ministry of Foreign Affairs of official documents issued by government/public agencies and local governments. Which procedure you should take will be determined depending on the destination country to which you are submitting your documents.
★If the destination country is one of the signatory nations of the Hague Convention, the document will be certified as "apostille", otherwise, the document will be certified as "authentication of official seals". An apostille and an authentication are the same thing in terms of getting a certification from the Ministry of Foreign Affairs, however, there is a difference in the procedures.

　
Note: It is recommended that you confirm with the submitting party in advance as to which kind of certification is required because the submitting party may specify a certification method or organization to receive attestation.

Difference between apostille and authentication of offcial seals

The procedure for acquiring an apostille allows you to skip the process of legalization by the consul of an Embassy/Consulate in Japan, which is necessary in the process of authentication of official seals. However, since documents issued by national university corporations are not treated as official documents, in case of an apostille, it is necessary to first go to a notary public office, and then to the Legal Affairs Bureau in order to certify that the document is equivalent to an official document, prior to submitting a request to the Ministry of Foreign Affairs.
On the other hand, in the case of an authentication of official seals, there is no need to do this, the document can be sent directly to the Ministry of Foreign Affairs to receive official seal confirmation. However, final consular certification will be required after getting proof from the Ministry.

Required Cases
・An authentication/apostille will be required when you need to submit Japanese official documents for various procedures in foreign countries and when its relevant agency asks you to obtain a certification from the Ministry of Foreign Affairs.
・It may also be required for certification by the consul of a foreign Embassy/Consulate (General) in Japan (legalization).

(E.g.) When an international student gains employment in their home country after completion of their study in Japan, there may be a case in which they are required to prove authenticity of the seals on documents issued by a Japanese university.

(Reference) Please refer to the following checklist to verify whether authentication or apostille is required.
→　Pre-application Checklist
　

●Authentication of official seals　　　　　　　　　　

(China, Indonesia, Vietnam, Malaysia, Egypt etc.)

An authentication is a certification from the Ministry of Foreign Affairs which is necessary to obtain legalization by the consul of an embassy/consulate (general) in Japan. After getting authentication of official seals from the Ministry, you have to obtain legalization by a consul at the relevant foreign embassy or consulate in Japan. Then you can submit the certified document to the relevant agency of the destination country.

Precautions

・In some cases, the relevant agency may require certification by the embassy or consulate-general of Japan in their local area, not an authentication by the Ministry of Foreign Affairs. Please note that documents which have already received an authentication by the Ministry of Foreign Affairs cannot be recertified by the local embassy or consulate-general of Japan.

・The Ministry of Foreign Affairs does not issue a document itself but certifies documents with an official seal, and makes such certifications on the official documents. Therefore, it is recommended to submit a document that can be sealed and stapled without problems. (E.g. a certificate of graduation or completion of studies etc.) We do not recommend direct certification for documents that can only be issued only once. (e.g. diploma etc.)

・University certificates issued by machines at convenience stores are not subject to official seal authentication. (As of September, 2021)

・Applications by mail from overseas will not be accepted.

・As the Ministry of Foreign Affairs verifies the identity of the applicant by returning the certified document to their address, the Ministry cannot send the document to any person other than the applicant.

・If you apply to the Ministry of Foreign Affairs for more than one certification at a time, you may be asked to explain where you are submitting your documents and why you need more than one certification.

Application Process
Application by postal mail/at the counter (Headquarters of the Ministry of Foreign Affairs (Tokyo)/Liaison Office (Osaka)

Application Fees
There is no application fee when sending to the Ministry of Foreign Affairs, only postage will be required separately.
Fees at each embassy and consulate will be required. (The fees vary depending on the embassy or consulate.)

References
Web page of the Ministry of Foreign Affairs
Frequently Asked Questions
　

●Apostille　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　

(United Kingdom, United States of America, India, Korea, South Africa etc.)

An apostille is a certification by the Ministry of Foreign Affairs in the form of an allonge (= apostille) under the Convention Abolishing the Requirement of Legalization for Foreign Public Documents (or Hague Convention). Legalization by a consul is not required. (It can be used as a certification equivalent to legalization by the Embassy/Consulate (General) in Japan.) However, since documents issued by national university corporations are not treated as official documents, it is necessary to first go to a notary public office, and then to the Legal Affairs Bureau in order to certify that the document is equivalent to an official document. After completing these procedures, you are able to apply to the Ministry of Foreign Affairs.

Precautions

・An apostille will only be accepted by signatory countries of the Hague Convention.

・Even if the destination country is a signatory to the Hague Convention, legalization may be required in some cases.

・All certifications submitted to non-signatory countries of the Hague Convention should be an authentication.

・As the Ministry of Foreign Affairs verifies the identity of the applicant by returning the certified document to their address, the Ministry cannot send the document to any person other than the applicant.

・If you apply to the Ministry of Foreign Affairs for more than one certification at a time, you may be asked to explain where you are submitting your documents and why you need more than one certification.

(In the case of national university corporations)
Cases that can be directly certified by the Ministry of Foreign Affairs (〇) Cases that cannot (×)

Application Process
Concrete Example: If you want to get an apostille for your diploma issued by Hiroshima Univ.
① Call a notary public office and make an appointment.
　(Higashi-Hiroshima City) Higashi-Hiroshima Notary Public Office (4th floor of Sun-square)
　　　　　　　　　　　　　　　　Tel: 082-422-3733
　(Hiroshima City) Hiroshima Notary Joint Public Office (Naka-machi, Naka-ku)
　　　　　　　　 　　　　　　　 Tel: 082-247-7277
*In some cases, notary offices do not have staff members who speak foreign languages, therefore it is recommended that you be accompanied by someone who sufficiently understands Japanese.
　　　　　　　↓
② Go to the notary public office on the day of your appointment with all the necessary documents listed below.
Necessary Documents:
1. Diploma (original)
2. Diploma (copy)
3. Declaration form* (Leave the signature box blank as you will be required to sign in front of a notary.)
　　*Sample declaration (if you are having a copy of your diploma certified by a notary)
4. Passport
5. Residence card
6. Commission fee: 11,500 yen per copy (for sworn certification in foreign languages)
(Commission fees differ depending on the method of certification, and the fees are designated by law.)
　　　　　　　↓
③ File by hand or postal mail to Hiroshima Legal Affairs Bureau in Hiroshima (inside the building of Hiroshima Government Legal Complex)
(*In this step, it is necessary to get verification from the chief of the Legal Affairs Bureau that the notary in charge of the document is a notary who belongs to the Legal Affairs Bureau and that his or her seal is genuine.)
Application fee: free (Postage will be required separately.)
　　　　　　　↓
④ Request apostille from the Headquarters of the Ministry of Foreign Affairs (Tokyo) or Liaison Office (Osaka) by hand or postal mail.
Necessary documents to be submitted to the Ministry of Foreign Affairs (by hand or post)
　

References
The Ministry of Foreign Affairs
Frequently Asked Questions
　　

Others
One-stop service: You are able to complete all of the procedures for an authentication and an apostille at one time at notary public offices in Tokyo, Kanagawa, Shizuoka, Aichi and Osaka, without having to undergo the process of the Legal Affairs Bureau and the Ministry of Foreign Affairs.
However, final legalization is required in the case of authentication of official seals.