To provide a window glass installation structure enabling the assured adjustment and fixing of a window glass securing position and providing high working efficiency while reducing manufacturing cost by commonizing a window glass fixing door and a window glass lifting door.

In this window glass installation structure, a detachable adjuster 20 which restricts the guide of a window glass 1 by a guide means 10 and adjusts the installation position of the window glass 1 in the lifting direction is installed between the window glass 1 attached to a door 2 which closes an opening formed in a vehicle 3 and a guide means capable of guiding the window glass into an internal space 8 formed between the inner panel 6 and the outer panel 5 of the door 2.