A window device of a cab main body (1) of a construction machinery comprising vertical guide rails (2) and horizontal guide rails (3) disposed continuously from a front opening part to a roof part of the cab main body (1), wherein rollers (5) pivotally supported on the lower part of a front window (4) and rollers (6) pivotally supported on the upper part of the front window (4) through link lever mechanisms (22) are press-fitted movably to these guide rails (2 and 3), and the link lever mechanism parts (22) rotate link levers (32) forcibly in such a direction that the upper rollers (6) are moved away from the front window (4) moved to a closed position so as to press the front window (4) against a weather strip (9) for preventing entry of rain water.
