PURPOSE: To output a voice of the same tone quality independently of the sound volume by controlling the degree of amplification of a variable amplifying part in accordance with an external sound volume request signal or sound volume level data prepared in a device.

CONSTITUTION: An external interface 5 is provided which receives the sound volume request signal, which designates the sound volume level, and a voice output request signal. A variable amplifying part 6 is provided which amplifies the audio signal from an audio D/A converting part 2 and supplies it to a speaker, and an amplification degree control part 7 is provided which controls the degree of amplification of the variable amplifying part 6 in accordance with the sound volume request signal obtained through the external interface part 5. That is, the degree of amplification of the variable amplifying part 6 is controlled by the external sound volume request signal. Thus, the output sound volume is freely changed for each voice message and a voice of high quality is supplied.