In a force sensor according to one embodiment, a main body is cylindrical. A cylindrical movable body is movable with respect to the main body and includes at least three circular openings in the outer circumference thereof. A strain body is fixed to the main body and the movable body and is deformable according to the movement of the movable body. Strain sensors are provided on the strain body. A first stopper is arranged inside each of the openings and includes a first outer circumferential surface including a first outer diameter less than a diameter of the opening. A cylindrical second stopper is arranged separate from a first inner circumferential surface of the main body by a first distance, includes a second outer circumferential surface of a second outer diameter less than a diameter of the first inner circumferential surface.