Abstract: Power can be efficiently generated in accordance with the amount of water in a channel by including: a first headrace channel positioned on an upstream side; a second headrace channel positioned on a downstream side; a water wheel on a most downstream side of the first headrace channel and the second headrace channel, the water wheel having a rotation shaft in a direction orthogonally intersecting with a water flow; a lateral movement apparatus that enables the second headrace channel to be moved in an upstream direction or a downstream direction; and a vertical movement apparatus that enables the water wheel to be moved in a vertical direction.