To provide a cleaning method easily cleaning pipes with sedimented setting substance fixed on inner walls thereof at site, and a cutting apparatus for the sedimented setting substance inside the pipe used in cleaning.

This cutting apparatus 30 has a vacuum pump 20 attached to a pipe Z at the rear end part of a drain pipe 10 to be cleaned, and is equipped with a cylinder 31 provided with multiple air vent holes 31p at a front side, a piston 32 slidably disposed inside the cylinder 31, a scaling member 33 disposed at the front side of the piston 32, having multiple blade parts 33z at the outer periphery thereof, with tip ends thereof abutting on the inner wall of the drain pipe 10, and a rubber packing 34 attached to the rear side of the cylinder 31. In this cleaning method, the cutting apparatus 30 is inserted into the drain pipe 10, compressed air is sent from a pipe A into the drain pipe 10 by a compressor 40 to slidably move the cutting apparatus 30 to cut off the sedimented setting substance in the pipe, cut chips are sucked by the vacuum pump 20 and collected in a collection tank 50 interposed at the rear stage of a pipe F.