To adjust the vertical angle of a footrest in the front/rear directions to fit the angle of feet of a person sitting on the seat of a chair.

The footrest 19 is mounted on the upper side of a member 15 for supporting the footrest 19 via an elastic member 18, so that the footrest 19 can be turned upward/downward with the elastic member 18 as the fulcrum and against the elastic force of the elastic member 18. The elastic member 18 is made of vibration-proof rubber. The member 15 for supporting the footrest 19 is mounted in such a way that the member can be rotated forward/backward relative to the seat 10 of the chair.