To provide a fall sensor suitable for practical use capable of reducing size and maintaining stable operation for a long period.

The fall sensor is composed of a coil spring 9 formed by connecting and fixing its movable electrode 5 sealed in a conductive container 2 as a fixed electrode to the inside of an end part of a conduction pin 4, of which, an end part is inserted into the container 2; and a weight 10 fixed to a free end of the coil spring 9. The length of the laterally oblong cylinder-shaped weight, extended from the free end of the coil spring 9 in a longitudinal direction, is made longer than its diameter.