PROBLEM TO BE SOLVED: To provide a small-sized and lightweight activity amount measuring apparatus suppressing consumption of a battery and having sufficient waterproof function.SOLUTION: The activity amount measuring apparatus includes: activity amount calculation means 30 including an acceleration sensor 32, a microprocessor 31, and a memory 33； an antenna coil 10； a near field communication chip 20； first switch means 41； and second switch means 42. The first switch means 41 sets a first contact M1 into a closed state on the basis of a detection signal S1, connects a grounding conductor G of the activity amount calculation means 30 to a minus potential line Vs, and makes the activity amount calculation means 30 actuate. When being actuated, the activity amount calculation means 30 immediately outputs an input holding signal S2 to the second switch means 42 on the basis of an internally-stored program. The second switch means 42 inputs the input holding signal S2 and, overlapped with the first contact M1 of the first switch means 41, sets a second contact M2 in a closes state.SELECTED DRAWING: Figure 1
