To provide a method and an apparatus for cutting a pipe, in which an end of the thin walled metal pipe at rest can be cut without having any residual chips on a cut surface or without generating radial deformation of the cut surface.

An outer blade 1 has an inner peripheral face 11 in contact with an outer peripheral face 101 of a cylindrical pipe 100 and a blade face 12 perpendicular to an axial direction X of a circle. An inner blade 2 has a circular outer peripheral face 21 facing an inner peripheral face 102 of the cylindrical pipe 100 and a blade face 22 perpendicular to the axial direction X. The outer blade 1 and the inner blade 2 are arranged in such a manner that the blade face 12 and the blade face 22 face each other on the cut surface CP. The inner blade 2 is supported to rotate around its own axis. While moving the inner blade 2 on a circular orbit 25 with a maximum diameter D2 larger than an outside diameter D1 of the cylindrical pipe 100 around an axis 24 eccentrically deviated from a center 23 by a prescribed length 1, the inner blade 2 is radially moved from a position where the outer peripheral face 21 has no contact with the inner peripheral face 102 of the cylindrical pipe 100 to a position where a circumference of the circular orbit 25 is entirely exposed outside the cylindrical pipe 100.