A method includes positioning a linear cutting edge inclined at an angle greater than 0° and smaller than 90° with respect to a Z axis at a cutting start position displaced from a position on an X axis along a direction of a Y axis in a three-dimensional orthogonal coordinate system in which an axial line of rotation of a rotation symmetry plane is defined as the Z axis, an axis in a radial direction of the rotation symmetry plane is defined as the X axis, and an axis orthogonal to both of the Z axis and the X axis is defined as the Y axis and machining the rotation symmetry plane by feeding the cutting edge from the cutting start position along a track having an X axis component, a Y axis component, and a Z axis component while the cutting edge is in contact with a rotating machine component.