storing a desired zone out of the 30 zones as an assigned city which stores the zone numbers in the example a reference numeral 5 denotes a display unit for displaying date time and city number of the aforementioned main cities and assigned cities 6 denotes a home city storage circuit for storing a desired city out of the aforementioned main cities and assigned cities as a home city 7 denotes a timer circuit for counting the time when a time of a city other than the home city is displayed on the display unit 5 and for generating an output when a predetermined time is counted and 8 denotes a seesaw type set switch for adjusting the time of each main city and setting the time of the assigned city a reference numeral 9 denotes a register for loading tentatively the zone number in which the assigned city is present which is used for setting the assigned city a reference numeral 10 denotes an assigned city set switch for obtaining the time of the assigned city stored in the assigned city storage circuit 4 and 11 denotes an inhibit circuit for detecting whether or not the zone number loaded in the register 9 comes within the range 1 to 30 and inhibiting it from being set outside the range a reference numeral 12 denotes a control circuit comprising a central processing unit cpu operating on signals.