PURPOSE: To provide a brush rotating mechanism capable of adjusting optionally the brush height and simple in structure in a disc type brush part of a cleaning device intended particularly for cleaning glass base plate.

CONSTITUTION: A rotary shaft is of a double structure made up of a tubular shaft 2 for rotating a brush and an inner shaft 1 within the tubular shaft for adjusting the height of the brush. The tubular shaft 2 transmits rotary action to a brush part 8 through a torque transmitting piece 7 and the inner shaft 1 is threadedly movable by a threaded part 4 in the axial direction and is in facial contact with the brush part 8. The top end of the inner shaft 1 is composed of only a collar 3 capable of being fastened to the top end with a setscrew 6 and the collar 3 is graduated to know the amount of the inner shaft 1 screwed in, i.e., the brush height.