A beveling method for beveling the edge of the opening of a cross hole (2-1) formed in a workpiece (W) while rotating a conical tool (1), which has conical cutting blade sections (11-1, 11-2), wherein beveling is carried out so that a surface of the same width is formed on the edge of the opening of the cross hole (2-1) by controlling the height of the conical tool (1) and/or the position of the rotation shaft of the conical tool (1) on the basis of a conic section, which is generated when a cutting blade section (11-1, 11-2) is cut with an imaginary plane (V) that contacts the processing point (P) of the conical tool (1) on the cross hole (2-1), and the shape of the edge of the cross hole (2-1) opening.