Device for comparing external time and local time to generate electronic time stamp and method thereof

A device for comparing an external time and a local time to generate electronic time stamp and a method thereof are provided. By requesting an external time from an external time source after receiving an time stamp request, generating a signature time based on the external time when determining the external time and a local time match an allowance interval, and signing a to-be-signed data contained in the time stamp request and the signature time to produce time stamp data, the system and the method can increase difficulty of tampering with signature time, and can achieve the effect of shorten detection time of signature time id tampered with.