A shock absorber comprising: a cylinder provided with a piston which is movable along an axis (CL1) inside the cylinder ; a spring provided coaxially with the cylinder ; a receiving member receiving the spring and provided to be movable in an axial direction of the cylinder ; a sensor configured to detect a position of the receiving member ; and a coupling member coupling the receiving member and the sensor , allowing rotation of the receiving member around the axis (CL1), and allowing a movement of the sensor along the axial direction, characterized in that : the sensor includes a coil portion formed by winding a conductive wire, a movement of the coil portion being restricted, and a core portion being movable along the axis (CL1) together with the coupling member , at least a part of the core portion facing an inner side of the coil portion ; the coupling member is formed integrally with the core portion ; and a recessed portion is formed in one of the receiving member and the coupling member , a protruding portion facing the recessed portion is formed in the other one of the receiving member and the coupling member , and the receiving member and the coupling member are coupled to each other via the recessed portion and the protruding portion . a cylinder provided with a piston which is movable along an axis (CL1) inside the cylinder ; a spring provided coaxially with the cylinder ; a receiving member receiving the spring and provided to be movable in an axial direction of the cylinder ; a sensor configured to detect a position of the receiving member ; and a coupling member coupling the receiving member and the sensor , allowing rotation of the receiving member around the axis (CL1), and allowing a movement of the sensor along the axial direction, characterized in that : the sensor includes a coil portion formed by winding a conductive wire, a movement of the coil portion being restricted, and a core portion being movable along the axis (CL1) together with the coupling member , at least a part of the core portion facing an inner side of the coil portion ; the coupling member is formed integrally with the core portion ; and a recessed portion is formed in one of the receiving member and the coupling member , a protruding portion facing the recessed portion is formed in the other one of the receiving member and the coupling member , and the receiving member and the coupling member are coupled to each other via the recessed portion and the protruding portion . the sensor includes a coil portion formed by winding a conductive wire, a movement of the coil portion being restricted, and a core portion being movable along the axis (CL1) together with the coupling member , at least a part of the core portion facing an inner side of the coil portion ; a coil portion formed by winding a conductive wire, a movement of the coil portion being restricted, and a core portion being movable along the axis (CL1) together with the coupling member , at least a part of the core portion facing an inner side of the coil portion ; the coupling member is formed integrally with the core portion ; and a recessed portion is formed in one of the receiving member and the coupling member , a protruding portion facing the recessed portion is formed in the other one of the receiving member and the coupling member , and the receiving member and the coupling member are coupled to each other via the recessed portion and the protruding portion . <EOS>