To reduce the power-supply capacity of a backup power supply used to perform a clocking operation continuously when a power failure occurs in a clock device which uses a commercial power supply as a power supply.

A clock device is provided with an osicllator 11 by a quartz oscillator, with a counting display 12 and with a radio time-signal or broadcasting receiver 13, hours are displayed, and the counted value of the counting display is corrected by a radio time signal or a by a broadcasting time signal. The clock device is provided with a low-power-consumption oscillator 21 and with a low-power-consumption counter 22. In a power failure, the low-power- consumption oscillator 21 and the low-power-consumption counter 22 are operated by a backup power supply 24. When the power failure is restored, the counted value of the low-power-consumption counter 22 is set on the counting display 12.