PURPOSE: To prevent rainwater from flowing up to the front portion from the rear portion of a cabin by pivotally installing a lower rear window on a lower frame, and providing a flume portion having a water discharge port outside the pivotally installed portion while continuously providing a one-step higher lateral frame outside the flame portion.

CONSTITUTION: In the cabin of a riding agricultural machine, rear windows 23, 24 which are divided up and down are provided between pillars in the rear of a seat. In this case, a lower frame 20 and a middle frame 21 are installed between the rear pillars. The upper rear window 23 is provided on the upper portion of the middle frame 21 with its upper portion being pivotally installed. The lower rear window 24 is pivotally installed on the lower frame 20 via a hinge portion 25 on the lower portion of the middle frame 21. Further, a flume portion 27 having a water discharge port 26 is provided on the lower portion of the lower rear window 24, while continuously providing a one-step higher lateral frame 28 in the rear of the flume portion 27. On the other hand, a seal portion 32 which is elastically brought into contact with a window glass 29 and a seal portion 34 which is elastically brought into contact with the lateral frame 28 are installed on a window flame 30.