Abstract: In a torsion beam suspension including: a pair of left and right trailing arms 1; a torsion beam 2 providing connection between the trailing arms 1; and gussets 3 which are U-shaped in section and substantially triangular in plane view and which are welded to inner side surfaces of connecting portions between the trailing arms 1 and the torsion beam 2, seat surfaces 9 are formed by crushing at left and right opposite end portions of a rear wall 2a of the torsion beam 2, the seat surfaces 9 being offset forward from a general outer surface of the rear wall 2a by an amount e larger than a plate thickness t of the gussets 3, and each gusset 3 includes an inner end edge portion 3d superposed on an intermediate portion in a lateral direction of the seat surface 9, and upper and lower front edge portions 3c, 3c connected by a weld W3 to upper and lower portions of an outer surface of the torsion beam 2.