To provide a cleaning device capable of removing a substance adhered to a wall surface of a water channel in a hydraulic power station safely without stopping operation of the hydraulic power station.

This cleaning device 1 for removing the substances such as aquatic organism and sludge or the like adhered to the wall surface 25 of the water channel 23 in the hydraulic power station is provided with a self-propelled vehicle 2 capable of running by itself on a bottom part 24 of the water channel 23 along a grade of the water channel 23, a float 7 capable of floating on the surface of water flowing in the water channel 23, a connection means 16 connecting the float 7 with the self-propelled vehicle 2 to move the float 7 on the surface of water in the interlocking relationship with the self-propelled vehicle 2, a brush body 10 provided on the float 7 and having a brush 1 capable of abutting on the wall surface 25 of the water channel 23, and a driving source 13 provided on the float 7 to vibrate the brush 12.