To start energizing a sensor in advance for immediate measurement at a time zone by noting that preferably excreta should be measured periodically at an approximately determined time zone to check the transition of a health state, to stop the energization to the sensor after the measurement is completed, and to greatly reduce the energization time to the sensor.

In an excreta measuring apparatus mounting the sensor for detecting or measuring constituents contained in the excreta of a user obtained by easing nature in a toilet, switching is made from a state where at least the sensor is not energized to a state of energization automatically from specific time for starting. A standby state is set to gather and measure samples. After measurement for a specific number of times or specific time passes, the energization to the sensor is stopped for returning to a state before start-up, thus preventing the sensor from being continuously energized for use without any difficulties.