A hydroformed product obtained by integrally working a metal pipe material by cold plastic working, which product (x) has a bent part at least at one location, (y1) has, at least at one location of the bent part, an expanded part of dimensions of a direction toward the outer side (or inner side) of the bend in a cross-section vertical to a pipe axis and a direction vertical to that direction of at least 1.35× of a circle equivalent diameter of an end of the metal pipe, and (z1) has an inner side (outer side) of the bent part of substantially the same radius of curvature.