An audio data synthesis method including a time of a plurality of audio data is adjusted without using a device which can acquire the standard time. Specifically, audio data is obtained based on synchronized recording of the first and second recorders without using standard time. A time difference is calculated between an own terminal and another terminal, based on the time at which output of a first sound from the audio output module is started, a time at which input of a sound corresponding to the audio data to the audio input module is started, a time indicated by the first information, and a time indicated by the second information. Second and third audio data is synthesized after a time difference between the second and third audio data based on the third sound which is input to the audio input module is adjusted, based on the time difference.