To provide a system capable of detecting leaps and falls of a human body at low electric power consumption and low costs by simple processing.

The fall determination system is constituted of an acceleration sensor for detecting acceleration in triaxial directions; an acceleration composing device for composing acceleration; a leap determination device for determining leaps; and a fall determination device for determining falls. Leaps and falls are determined on the basis of the size of composed acceleration in this invention. It is possible to distinguish reductions in acceleration caused by a leap from those caused by a fall by determining that one is in the process of leaping for a prescribed period of time after the detection of acceleration determined as a takeoff for a leap. It is possible to assume that the acceleration is caused by a fall without the determination that one is in the process of leaping during reductions in acceleration, and the continuation of reductions in acceleration for a prescribed period of time is determined as a fall. Since it is possible to distinguish leaps from falls on the basis of the size of acceleration, it is possible to implement the fall determination system which does not require complicated computations.