A disturbance alarm comprising a hollow tubular case having upper and lower electrical contact plates fixedly positioned therein. A pendulum assembly includes a lower weight which rests upon the flat upper surface of the lower contact plate, an upper weight and a rigid shaft fixed to the weights and spacing the weights from each other. The upper electrical contact plate encircles the pendulum shaft and is adapted to make electrical contact therewith to close an electrical circuit through an alarm device. A collar is slidable within the case for clamping the lower weight onto the contact plate such that the pendulum is balanced thereon out of electrical contact with the upper contact plate. A magnet encircles the pendulum shaft adjacent to the upper weight for attracting and holding the pendulum in electrical contact with the upper plate when such balance is disturbed and an alarm condition is thereby detected.