To provide a well water usage measuring apparatus capable of accurately computing the usage of well water by measuring the operating time of a pumping motor in a measuring means that measures the usage of well water by installing a measuring instrument for each storage pump and charges a sewerage rate corresponding to the water usage.

A well water usage measuring apparatus includes an energization detecting part 3 that can clamp an electric wire 7; a time recording part 4 having an hour meter; and a water usage computing part 5. The energization detecting part 3 has an endless core 32 separated to be openable/closable in part and wound with a coil, and includes an operation control part for generating an induction current in the coil when a current flows into the electric wire arranged in the endless core 32, and controlling the operation of the hour meter using the induction current when the current flowing in the electric wire is a current of a threshold value or more. The time recording part 4 integrates the operating time of the storage pump 2 by the operation of the hour meter, and the water usage computing part 5 computes the usage of well water on the basis of the operating time of the storage pump 2 integrated by the time recording part 4.