Secret recordings are powerful evidence in cases involving power harassment, infidelity, or labor disputes. However, the questions always remain: “Is it illegal to record without the other person’s consent?” and “Can the recording be used as evidence in court?”
As of 2025, the legal conclusion in Japan is clear. In short, secret recording conducted by a party to the conversation is, in principle, completely lawful and not subject to criminal penalties. The Supreme Court has consistently upheld this position. Furthermore, the recorded evidence is almost 100% likely to be admitted as evidence in any civil, criminal, or labor dispute.
Summary of Legal Rules for “Secret Recording Without Consent” in Japan
| Item | Conclusion | Basis/Key Points |
| Is the act of recording itself illegal? | No (Generally free) | No corresponding crime in the Penal Code. The Supreme Court has clearly stated that “it is not illegal for a party to a conversation to record that conversation without consent” (e.g., Supreme Court Decision, December 18, 2001, and many others). |
| Is it OK without consent? | Completely OK without consent | Recording silently is fine if there is a “justifiable reason.” Protecting one’s own rights or preserving evidence is almost 100% justifiable. |
| What if a third party records secretly? | Case-by-case (Potential for illegality) | If a non-party records using a wiretap, it may violate the Radio Law or the Wire Telecommunications Act. |
| Can the recording be submitted as evidence in court? | Yes (Almost 100% valid) | It is generally determined not to constitute “illegally obtained evidence” in civil, criminal, or labor disputes. |
| What if the recording is published/spread online? | Case-by-case | There is a risk of being sued for defamation or invasion of privacy. The act of recording is separate from the act of publishing. |
| What if the company’s work rules prohibit recording? | The recording itself cannot be prohibited | Even if prohibited by work rules, it is only a private contract and does not lead to criminal liability. It may be grounds for disciplinary action, but “recording = illegal” is not true. |
| Should I inform the other party beforehand? | Not required, but safer in practice | Informing them risks them shutting up, but declaring “I am recording this recording” makes it harder for them to later claim “consent was given.” |
| What if the other party demands “Do not record” or “Delete it”? | You can refuse (No legal basis for forced deletion) | Similar to the Taichi Kokubun case. There is no obligation to comply with demands for forced deletion. |
| Exceptional cases where it becomes illegal | ① Secret filming of sexual parts while recording. ② Third party recording with a wiretap. ③ Recording for the purpose of threat/extortion and demanding money. | In these cases, it is not the recording itself but other associated crimes that are established. |
Three “Golden Rules” Commonly Cited in Practice
- If you are a party to the conversation, secret recording is almost 100% safe.
- You have no obligation to delete the recorded data, even if the other party demands “Delete it” afterward.
- If the case goes to court, the recording will almost certainly be admitted as evidence.
Recent Famous Examples (Reference)
- Taichi Kokubun (2025): NTV sought the deletion of a recording, but there was no legal basis for the demand.
- GaaSyy Former Diet Member Case: Found guilty due to recording for the purpose of threat + publishing (the act of recording itself was not the crime).
- Numerous Power Harassment Lawsuits: The audio secretly recorded by the victim became the decisive evidence, leading to a win.
✅ Summary
In Japan, “secretly recording a conversation in which you are a participant” is almost entirely free from legal restrictions.
You are allowed to ignore demands like “Don’t record” or “Delete it” (though caution is necessary in workplaces where there is a risk of disciplinary action).
