To provide a dust proofing device for pipe cutting work for preventing invasion of chips or the like into a metal pipe in cutting work of a section of the metal pipe (steel pipe).

A circular cushioning member 7 is provided along an outer circumference of a disc-shaped reinforcement plate 3 having a hole at a center. A plurality of tube receiving arms 8 are provided along an inner diameter of the cushioning member 7, and a tube 11 is installed. A fixed pipe 1 is fixed to the hole, and an air feed pipe 4 having a socket 2 with a check valve at an end is inserted into the fixed pipe 1. A tip of the air feed pipe 4a inserted is connected through a tube joint 10 to the tube 11.