PURPOSE: To reduce power consumption, by operating a sounding circuit, only during the period of generation of alarm signal, in such a manner as to control a power source driving transistor by a switching transistor.

CONSTITUTION: When an indicating element of liquid crystal, etc. is driven and the alarm signal is put into an alarm terminal 3 of a clock driving LSI2 which is to generate the alarm signal at a preset time, the switching transistor 7 repeats ON- OFF motions, base potential of a power source driving transistor 8 is raised through a capacitor 11, and the transistor 8 is turned on. And power is supplied to a sounding circuit 5 from a DC power source 1 and the alarm signal is generated from a speaker 6. And therefore, since power sonsumption in the sounding circuit 5 is confined to the alarm signal generating period, consumption of battery, etc. can be largely reduced.