PURPOSE: To drive a sounding body by the sound volumes differing with time zones by logically synthesizing decoder outputs thereby obtaining the time announcement control signal and time announcement change-over control signal.

CONSTITUTION: An AND gate 6 is inputted with the output of a decoder 5b and the AM output from a counter 4e and an AND gate 8 is inputted with the output of the decoder 5b and the PM output of the counter 4e. The time announcement change-over control signal is obtained by the outputs of the both gates. An AND gate 10 is inputted with the output of the decoder 5c and outputs the time announcement control signal. A gate 11 and FF12 are inversion-operated by the outputs of the gates 6, 8 and the sounding body 18 such as buzzer outputs the time announcement sounds of the sound volumes differing according to the time zones by the logical products 15, 16 of the time announcement control signal obtainable in the output of a time limit circuit 14 and the time announcement change-over control signal from an FF12.