Abstract: A clock device comprising a clock signal oscillator, a time zone selection circuit for detecting a selected point when performing an operation for selecting a time zone, a reference time zone circuit for determining a reference time zone, a detector circuit for detecting the beginning of the operation for selecting a time zone, a timer circuit adapted to operate when receiving an output from the detector circuit, a time difference signal circuit for generating a desired time difference signal by receiving signals from the time zone selection circuit, the reference time zone circuit and the timer circuit, an adder circuit for adding output signals from the clock signal oscillator and the time difference signal circuit, a decoder for decoding an output of the adder circuit, and a display circuit for displaying the time at the selected point and adapted to operate by receiving an output of the decoder.