Provided is a cylinder cleaning apparatus having a structure suitable for size reduction and slimming of the apparatus. Thick sections (10b, 10c) of a pressing pad (10) are attached to attaching sections (42, 43) of a support bar (40), a side plate (50) is arranged outside the thick sections (10b, 10c), and the pressing pad (10) and the support bar (40) are sandwiched and held between the side plates (50) on the both sides.