Disclosed is a torsion beam type rear suspension which comprises a pair of right and left trailing arms (2), a torsion beam (3), and a spring seat (6) disposed in a corner region defined at a junction between each of the lateral ends of the torsion beam and a rear portion (2c) of a corresponding one of the trailing arms to form a mounting seat for a coil spring (8). A vertical flange (13) is formed along a laterally inner edge (12) of the spring seat to have a longitudinally front edge extending vertically along a rear side surface of the torsion beam. The spring seat has a first region (7b) of disposed opposed to the corresponding trailing arm and fixed thereto approximately in its entirety, and a second region (16) disposed opposed to the torsion beam and fixed thereto only through the vertical flange. The torsion beam type rear suspension of the present invention can improve the supporting rigidity of the spring seat relative to a coil spring without increasing the rigidities of the spring seat and trailing arm themselves, while allowing the risk of stress concentration occurring at an end of the torsion beam to be reduced, so as to achieve increased chassis rigidity and adequately maintain suspension functions.