PURPOSE: To effectively absorb impact load without contracting the crush stroke by a door glass guide member.

CONSTITUTION: A door rear part frame 20 is formed into a U shape in section, and the rear end edge of a rear door glass is slidably inserted into a door glass run arranged on the inner periphery. Elongate holes 44 verticallty extended as a stiffness decreasing means is vertically bored on a rear wall part 20A of the door rear part frame 20 at the fixed distance, and the part on which the elongate holes 44 of the door rear part frame 20 are bored has stiffness to the load to act in the car width direction lower than that of the other part, and they are easily crushed as shown by the imaginary line in applying of load.