PURPOSE: To ensure good field of view and appearance by fixing door glass to the outer surface of a door frame, thereby omitting necessity of providing the inner circumferential edge for mounting door glass on the inner circumferential part of the door frame, thus enlarging the inner circumferential side of the door frame, and thereby eliminating a part exposed to the outside of an intermediate strut.

CONSTITUTION: The window structure of a cabin comprises a front strut 10, an intermediate strut 11, and a rear strut 12. A door frame 20 is rotatively supported around vertical axis on the intermediate strut 11 through a pivotal fitting 22. A door glass sheet 20 is provided on a door frame 19. A rear side glass sheet 17 is provided between the intermediate strut 11 and the rear strut 12. The door glass sheet 20 is fixed to the outer surface of the door frame 19. The rear side glass sheet 17 is fixed to the outer surface of the intermediate strut 11. The door glass sheet 20 and the rear side glass sheet 17 are placed in close proximity to one another on the common surface. The provision of an inner circumferential edge for mounting the door glass sheet 20 is no more needed, and the purpose is thus achieved.