Is 立会人型 legally weaker than 当事者型?

Not categorically. The 2020 cross-ministry Q&A recognised that 立会人型 can attract the Article 3 presumption where the authentication and internal processes are sufficiently unique to the user. In practice the strength depends on how a given service implements identity verification, so it is a per-service question rather than a per-model one.

Do all contracts in Japan allow electronic signature?

Most commercial contracts can be concluded electronically, but some categories have had statutory written-form or delivery requirements, and the rules have been amended repeatedly in recent years. Check the current requirement for your specific contract type with counsel rather than assuming blanket coverage.

Glossary

What is Electronic Signature Act (Japan)?

The Electronic Signature Act (電子署名法, Act No. 102 of 2000) is the Japanese law giving electronic signatures legal effect. Its Article 3 grants a presumption of authenticity to an electronic document signed by the principal using a signature only that person can perform — the provision that determines whether an electronic contract holds up in a Japanese court.

Last updated: July 27, 2026

Two service models are used in Japan, and the difference is who holds the signing certificate.

In the 当事者型 (principal-signature) model, each contracting party obtains its own certificate and signs with it. This maps most directly onto Article 3, but it requires every counterparty to complete identity verification and obtain a certificate — friction that stops many deals.

In the 立会人型 (service-provider-signature, also called 事業者署名型) model, the e-signature provider applies its own certificate at the instruction of the user, who is authenticated by email and other factors. This is the model most cloud e-contract services in Japan use, because the counterparty needs nothing but an email address.

The question of whether 立会人型 also attracts the Article 3 presumption was settled by joint government Q&A from the 総務省, 法務省 and 経済産業省 in 2020: it can, provided the uniqueness of the user's authentication process and of the provider's internal process are sufficiently assured. The 2020 cross-ministry material is published by the 総務省 (see sources). This is a summary, not legal advice — confirm the current text and consult counsel for your own contracts.

For procurement, the practical consequence is that 「電子契約に対応」 is not a single capability. Which model a tool uses changes what your counterparties must do, and that is often the deciding factor rather than price.

Sources: [1] [2]

Frequently asked questions

Is 立会人型 legally weaker than 当事者型?: Not categorically. The 2020 cross-ministry Q&A recognised that 立会人型 can attract the Article 3 presumption where the authentication and internal processes are sufficiently unique to the user. In practice the strength depends on how a given service implements identity verification, so it is a per-service question rather than a per-model one.
Do all contracts in Japan allow electronic signature?: Most commercial contracts can be concluded electronically, but some categories have had statutory written-form or delivery requirements, and the rules have been amended repeatedly in recent years. Check the current requirement for your specific contract type with counsel rather than assuming blanket coverage.

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