To provide mounting structure of a weather strip that reduces the width of an outer surface of an automobile door and the width of the gap between a door frame and a door opening edge of the vehicle body.

A recessed portion 18 having a substantially U-shape in section is formed on an outer surface of a corner portion 110 on the in-car side of a channel portion 11 having a substantially U-shape in section of a door frame 10 with a glass run 40 fitted and attached. A weather strip 50 is attached to the recessed portion 18 by engaging one end of a mounting base 51 of the weather strip 50 that is put along an upper surface of a closed section portion 15 of the door frame 10 formed on the in-car side of the channel portion 11, with the recessed portion 18. And a hollow seal portion 52 of the weather strip 50 that is located on an upper side of the closed section portion 15 is pressure- welded to a door opening edge of the vehicle body.