To provide a portable telephone, capable of realizing the stereophonic reproduction of sound such as music, by setting a large diameter speaker of a wide band and large volume.

A speaker 7 and a microphone 9 are arranged at the face of the portable telephone 1 opposite to the face where a display 2 and a control button group 4 are arranged, that is, the back face side of the portable telephone 1, so that the diameter of the speaker 7 and the microphone 9 equipped with a function as a speaker can be enlarged, and that sound reproduction with a wide band and large volume can be achieved. Also, the speaker 7 and the microphone 9 are formed of an equivalent flat speaker 8 (electric signal vibration converter), and the speaker 7 and the microphone 9 having the function as a speaker are allowed to cooperate together under the situation of the portable telephone 1 being used for sound reproduction so that those speakers can function as a stereophonic speakers. Thus, it is possible to realize the stereophonic reproduction of a sound such as music.