To provide a pipe cutting machine capable of cutting a pipe even of a large diameter efficiently in a short period of time, and achieving excellent economical efficiency and excellent durability with a simple, compact, and light-weight configuration.
A pipe cutting machine cuts a pipe 10 at a right angle to the center line of the pipe 10. The pipe cutting machine comprises: rotary blades 20, 20 in a pair, with a plane at a right angle to the center line of the pipe 10 to be cut defined as an x-y plane and the center of the pipe 10 defined as a coordinate origin, the rotary blades being arranged to face each other on both sides of a y axis in such a manner that blade edges of the rotary blades 20, 20 overlap each other in the direction of an x axis; a straightforward driving mechanism 50 that drives the rotary blades 20, 20 in a pair straightforward in opposite directions of a y-axis direction so as to make the rotary blades 20, 20 in a pair pass each other on the x axis and in the vicinity of the x axis; and a power direction conversion mechanism 46 and a power direction conversion mechanism 47 that change part of straightforward driving force in the y-axis direction to force in the x-axis direction and move the rotary blades 20, 20 in a pair outwardly to get farther from the y axis for avoiding interference between the blade edges when the rotary blades 20, 20 in a pair pass each other on the x axis and in the vicinity of the x axis.