Abstract: A silent alarm wrist watch is disclosed wherein the human wrist is vibrated directly by a vibration means at a preset alarm time. The vibration means are energized by an electric signal at a composite frequency made up of two or more frequencies (repetition rates), each selected from a range, one higher, one lower, and both in the range of 0 to 300 Hz. The invention permits low energy consumption of the electric power source in the watch, and effective recognition of the alarm vibration.