PURPOSE: To avoid damage of a window glass by receiving, with a back door base body a bending load which acts on the window glass when a back door is shut, via a spacer provided between the inner face of the window glass along the external circumference of a penetrating hole for a wiper driving axis bored on the window glass and the back door base body.

CONSTITUTION: In a window glass 20, a through hole 23 which allows penetration of a guide tube 32 which accommodates a rotation driving axis 31 of a wiper is provided. A lower packing 34b is fitted into this through hole 23 and a resin spacer 40 which surrounds the external circumference of the lower packing 34b is interposed between the inner face of the window glass 20 and the seat facing portion 17 of a back door base body 11. When a back door is shut, a wiper device 30 is going to move downward by its inertia, so a bending load is applied to the window glass 20. However, the load is immediately transmitted to the seat facing portion 17 of the back door base body 11 through the spacer 40, and it is dispersed to the side of an outer panel 12. Therefore, the damage of window glass 20 can be prevented.