PURPOSE: To allow automatic time setting coincident to time of a standard clock by providing an error detector for an error between measured time and standard clock time and an automatic speed adjuster of a governor of a generator.

CONSTITUTION: Current time is measured by a measuring apparatus 3 with the output frequency of a generator 1. Then the time of a standard clock 2 and time measured by the measuring apparatus 3 are input to an error detector 4, where the error is displayed on a display 5 and also the error value is input to a controller 7 of a governor 7. The controller 7 inputs a governor control signal according to the error value to the governor 10 to automatically adjust the output frequency of the generator 1. If the measured time is behind the standard time, the governor 10 is accelerated to raise the frequency to advance the time while if the measured time is too fast, the frequency is lowered to have the time delayed, so that it may coincide with the standard time.