To extend a battery service life by allowing a terminal user to optionally set an upper limit of a coding rate of a variable rate coding circuit provided to the terminal so as to reduce power consumption more regardless of a simple configuration.

In the case that a key pad 291 by the terminal user is operated to enter and set an upper limit of a coding rate to be set to a VOCODER 12 and a power saving mode designation button 293 is operated in this state, the power saving mode is set and a coding rate variable control means 133a of a microprocessor 13 is used to set a coding rate of the VOCODER 12 to the entered and set upper limit.