PURPOSE: To provide the side car body structure of a slide door car which is designed to improve support rigidity of a pillar through prevention of deformation of an opening formed in a side sill and prevent lowering of precision of fit-in between a pillar and a slide door.

CONSTITUTION: In the outer panel 11 of a center pillar 7, a sill coupling part 13 and the lower end part of a rear edge flange 22 are spot-welded and coupled to a sill outer 4 for coupling. Thus, a narrow part 18 and a vertical wall 19 are positioned in the vicinity of an opening part 8. An oblique wall 20 is formed in a manner to range from the vicinity of the front end of an opening part 8 to the rear edge part of 23 of the center pillar 7 with which a slide door is brought into contact during closing of a slide door. A closed section part vertically extended at the opening part 8 connected to the lower end of the center pillar 7 is formed on the inner side of the sill coupling part 13.