To secure parallelism of a supporting roller and a rotary shaft by forming a plurality of supporting parts journaling a rotary shaft on each side frame so as to be parallel with the supporting roller and journaling the supporting roller and the rotary shaft on the side frame at symmetrical locations.

A rotary shaft 9 mounted on a holder 3 is journaled on a supporting hole of each side frame 6 so as to be parallel with a supporting roller 7. Thus, because the holder 3 is connected with the rotary shaft 9 suspended over the side frame 6 and a supporting hole of the rotary shaft 9 and a supporting recessed part of the supporting roller 7 are formed at locations symmetrical to each side frame 6, the supporting roller 7 and the rotary shaft 9 suspended over each side frame 6 are always parallel. Therefore, even when the side frames 6 each other are not in a parallel state by small quantity and are fixed to a base frame 5, the side frames 6 are always parallel and orthogonality of a cutting blade 10a and a chamfering blade 10b relative to a center shaft of a pipe can be secured.