PURPOSE: To know an external correction position clearly and to confirm which time correction mode is set at present by characters marked on one transparent optical shutter among optical shutters, by arranging the optical shutters opposite to respective optical switches.

CONSTITUTION: An optical switch 46 consists of an optical switch 46a for obtaining the locked state of time correction, optical switches 46bW46d for time correction corresponding to the respective time correction modes of hour, minute, and second, and an optical switch 46e for prevention against malfunction. Further, optical shutters 48aW48d consisting of liquid-crystal display segments sectioned into four corresponding to the optical switches 46aW46d are provided to an LCD cell 34, and when an opaque optical shutter 48 is interposed, external irradiation light does not reaches the optical switches 46 to inhibit shielding control from outside of the optical switches 46. Further, characters "lock", "hour", "minute", and "second" are marked at the side parts of the optical shutters 48aW48d, and the operation state of only the optical switch 46 corresponding to the optical shutter 48 in an open state among four optical shutters is confirmed.