PURPOSE: To attain hand-free talking with sound quality and sufficient sense of quantity by constituting the hand-free telephone set with a microphone whose low sound frequency is decreased, a speaker outputting a middle and high sound frequency sound and a speaker outputting a low frequency sound.

CONSTITUTION: The telephone set is provided with a microphone 1 whose low sound frequency sensitivity is decreased, a speaker 23 built in a handset 2 and outputting a middle high sound frequency sound and a speaker 3 placed in an optional position in a cabin and outputting a low sound frequency sound. Thus, the frequency characteristic of the microphone 1 and the speaker 23 of the handset 2 is selected to be middle and high sound frequency and the frequency characteristic of the speaker 3 provided in the cabin is selected to be low sound frequency. Thus, the microphone is masked against noise in the cabin, the articulation of sound is ensured and the powerful sound output is obtained in this way.