An exercise assisting tool includes a seating surface on which a user is seated, and a body portion having a bottom surface formed in a substantially spherical shape. A height H of the seating surface at a lowermost point is set in a range from 100 mm to 450 mm, and a regulator is further provided to suppress any slippage of buttocks of the user from the seating surface. The exercise assisting tool is structured so that the user seated on the seating surface is allowed to tilt the seating surface in all directions while having the bottom surface in contact with the ground surface.