To provide a device which enables a penstock cleaning operation to be safely performed without the installation of a scaffold.

This penstock cleaning device 9 comprises a rope 6 which is long enough to be wound around the penstock 1, a dust removing means 7 which is provided for the rope 6 so as to remove dust 6, and a fastening means 8 for annularly fastening the rope 6 in the state of winding it around the penstock 1. When the rope 6 is pulled an at-hand side in a state in which the penstock cleaning device 9 is attached to the penstock 1, the dust removing means 7 goes around along a stiffener 4, and the dust 5 accumulated in a contact portion between the penstock 1 and the stiffener 4 is brushed off and cleaned by the dust removing means 7.