PURPOSE: To stabilize a transmission output by compensating the parameter of a transistor with a temperature coefficient connected to the output side of transmitting carrier detector, by applying a reference voltage of small power to a compensating diode, and by removing fine variation in transmission output.

CONSTITUTION: To the transmission output circuit connected between transmitting carrier detector 9 and driving amplifier 3, Darlington-connected transistors Tr11 and Tr12 and control Tr9 are connected and the temperature variation of base- emitter voltage VBE of Tr12 is compensated by Tr11. Further, resistance 15 and diode 14 connected in series are connected to the base of Tr12 and temperature characteristics of Tr12 and diode 14 cancel to increase the compensation effect of the variation caused by the temperature variation, thereby stably amplifying fine variation in voltage by the reference voltage of diode 14. Then, the control voltage of control Tr9 is stabilized and the stabilized transmitting power is sent out from antenna 7.