An exercise assisting device comprises foot supports having foot support surfaces respectively, a seat, a seat height adjusting unit, and a seat driving unit. The foot support is provided for bearing foot of a user. The seat is shaped to have a contact surface for supporting buttocks of the user when the user places the feet onto the foot support surfaces. The seat height adjusting unit is configured to move the seat toward a vertical direction and also toward a front-back direction in order to position the seat at a standard position which is located at a standard height from the foot support surface in the vertical direction. Consequently, a knee of the user has a predetermined angle. The seat driving unit is configured to swing the seat about the standard position so as to vary weight of the user which acts on legs of the user. The exercise assisting device further comprises a load regulating means. The load regulating means is configured to vary a load which acts on a knee joint of the user as a height between the contact surface of the seat and the foot support surface in the vertical direction becomes shorter than the standard height.
