PURPOSE: To provide an alarm clock for awaking a user surely at an alarm time or before by a constitution wherein the hands are moved to the alarm time a desired time before the alarm time.

CONSTITUTION: Upon setting an alarm switch 13, a random number generating circuit 9 is actuated to generate a random number Δt which is then subtracted from an alarm time data stored in the memory of a control circuit 10 and the difference is stored in the memory 2 of the control circuit 10. When the current time reaches the time stored in the memory 2, the control circuit 10 moves an hour hand 3, a minute hand 4 and a second hand 5 to an alarm time and emits an alarm sound through a speaker 8. Upon elapse of 20 sec after stopping the alarm sound by means of an alarm set switch 13, the hands 3, 4, 5 are returned to the positions indicating current time. The alarm sound is emitted again when a human body is detected at the alarm time.