To solve problems of conventional pipe cutting machines wherein when a rotating cutting blade is brought into contact with the peripheral wall of a pipe, vibration of the cutting blade is transmitted directly to the pipe and the pipe is rattled, and therefore, the cross section of the pipe becomes rough and burrs are produced.

In a pipe cutting machine, a pair of clamp means 1, 2 vertically holding the pipe P are installed at a predetermined interval S in the longitudinal direction, and a rotary cutting blade 4 reciprocatingly traversing between the fore-and-aft clamp means 1, 2 is installed. Each of the fore-and-aft clamp means 1, 2 comprises pipe receiving blocks 11, 12 which are installed on the same horizontal plane and in which V-grooves 11a, 12a supporting the lower half round part of the pipe P are formed and pipe retaining blocks 13, 14 which are vertically movably disposed on the pipe receiving blocks 11, 12 and in which V-grooves 13a, 14a pressingly supporting the upper half round part of the pipe P are formed. Each of the pipe retaining blocks 13, 14 is laterally swingably supported relative to vertical drive means 15, 16.