To provide a knee-bending cushion that can be easily assembled when the user sits straight with his knees bent and that can be adjustable in height according to differences in physique among individual users.

The knee-bending cushion is composed of a cushion having a first adhesive sheet 40 disposed on a side face portion, and a seat pillow 30 having a second adhesive sheet 50 disposed on a lower surface and having a grip portion 60 provided on a side face. The second adhesive sheet 50 of the seat pillow 30 is affixed to the first adhesive sheet 50 using the grip portion 60 and the seat pillow 30 is secured to the cushion 10.