PURPOSE: To enable correction of time in natural fashion by a time casting signal, by changing a pulse signal by a prescribed number of times in the direction of eliminating gradually an error detected by an error detecting means.

CONSTITUTION: A time casting signal contained in a broadcasting wave received by a radio set 4 is detected by a time casting signal detecting circuit 24. An error detecting circuit 25 detects an error of the hour of a clock 1 detected by an hour detecting circuit 23, in respect to the time casting signal detected by the circuit 24, and outputs a signal of change of a pulse interval corresponding to the error to a pulse changing circuit 22. When the time casting signal is detected after the hour of the clock, for instance, a control circuit 20 changes the interval of a pulse signal inputted to a driving means, so that it is made longer by the number of times corresponding to the error than a regular pulse interval. When an hour hand indicates the hour after the detection of the time casting signal, to the contrary, the control circuit 20 changes the interval of the pulse signal so that it is made shorter by the number of times corresponding to the error between them than the regular pulse interval. By this method, the error is eliminated gradually as the time passes.