To provide a drainage measuring box enabling a user to confirm that water for use supplied to a paddy field overflows from the drainage measuring box from a distance in spite of having an inexpensive and simple structure.

The drainage measuring box 5 is configured to include: a drainage pipe 10 draining the water for use supplied to a paddy field 4 through a water intake opening 3 from the paddy field 4; an exchanging part 20 exchanging energy of fluid of the water for use overflowing into the drainage pipe 10 from the paddy field 4 into mechanical energy; and a notification part 30 driven by the mechanical energy exchanged in the exchanging part 20. The exchanging part 20 is provided with: an impeller 21 rotating due to the flow of the water for use overflowing into the drainage pipe 10; and a support part 23 pivotally supporting the main shaft 22 of the impeller 21. The notification part 30 is provided with: a transmission mechanism 31 into which the rotary energy of the main shaft 22 is input; and a display part 32 the state of which is displaced by the energy transmitted from the transmission mechanism 31.