PURPOSE: To enable the required strength of a seatbelt anchor to be obtained without causing increase in weight.

CONSTITUTION: The bottom 1a of a seatbelt anchor 1 is made to abut to the bottom 103a of a rear pillar inner 103 and the bottom 2c of a reinforcement rear pillar 2 is joined to the bottom 104c of a rear fender 104 via a metal seal 4, and the flange portion 2a of the reinforcement rear pillar 2 located on one side of a sub-assembly member 3 is joined between the respective flange portions 103a, 104a of the rear pillar inner 103 and the rear fender 104. Further, the junction between the other side walls 2b, 1b of the reinforcement rear pillar 2 and the seatbelt anchor 1 on the other side of the sub-assembly member 3 is joined to the side wall 103d of the rear pillar inner 103.