A single day alarm clock includes circuitry for selecting an alarm mode to be an alarm-on mode or an alarm-off mode, circuitry for setting an alarm time at which an alarm will sound when the alarm mode is set to the alarm-on mode and circuitry for automatically setting the alarm mode to the alarm-off mode once the alarm has sounded in the alarm-on mode, thereby preventing the alarm from sounding the next day at the set alarm time.