PURPOSE: To avoid the wasteful power consumption caused by unnecessary time correcting actions by detecting the time correction quantity, and changing the interval time between the time correcting actions in response to the detected correction quantity.

CONSTITUTION: A time counting circuit 7 calculates the one-minute signals M from a frequency dividing circuit 6 to obtain the present time data, feeds the data to a CPU 1, and corrects the counted present time data with the time data from the CPU 1. A reception completion signal C is sent to a receiving circuit 3 to stop the receiving action of the circuit 3. The difference between the counted values of the counting circuit 7 before and after the present correcting action, i.e., the correction quantity, is calculated and stored in a RAM 9. The quotient of the correction quantity divided by the implementation interval time of a reception interval memory (RAM) 9, i.e., the correction quantity for a unit time (correction factor) is calculated and stored in the memory 9. It is judged in which range the correction factor falls against the prescribed values (a) to (c) (a>b>c>), then 1, 3, 12, or 24 hr is stored in the reception interval memory 9 as the implementation interval time, and the radio wave correction process is completed.