A shock absorber (20, 20A, 20B, 20C) comprising: a cylinder provided with a piston which is movable along an axis inside the cylinder; a spring provided coaxially with the cylinder; a receiving member (33, 133) receiving the spring and provided to be movable in an axial direction of the cylinder; a sensor (90, 90A, 90B, 90C) configured to detect a position of the receiving member (33, 133); and a coupling member (100, 140) coupling the receiving member (33, 133) and the sensor (90, 90A, 90B, 90C), allowing rotation of the receiving member (33, 133) around the axis, and allowing a movement of the sensor (90, 90A, 90B, 90C) along the axial direction, characterized in that: the sensor (90, 90A, 90B, 90C) 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 together with the coupling member (100, 140), at least a part of the core portion facing an inner side of the coil portion; the coupling member (100, 140) is formed integrally with the core portion; and a recessed portion (103, 133c) is formed in one of the receiving member (33, 133) and the coupling member (100, 140), a protruding portion (33c, 143) facing the recessed portion (103, 133c) is formed in the other one of the receiving member (33, 133) and the coupling member (100, 140), and the receiving member (33, 133) and the coupling member (100, 140) are coupled to each other via the recessed portion (103, 133c) and the protruding portion. a cylinder provided with a piston which is movable along an axis inside the cylinder; a spring provided coaxially with the cylinder; a receiving member (33, 133) receiving the spring and provided to be movable in an axial direction of the cylinder; a sensor (90, 90A, 90B, 90C) configured to detect a position of the receiving member (33, 133); and a coupling member (100, 140) coupling the receiving member (33, 133) and the sensor (90, 90A, 90B, 90C), allowing rotation of the receiving member (33, 133) around the axis, and allowing a movement of the sensor (90, 90A, 90B, 90C) along the axial direction, characterized in that: the sensor (90, 90A, 90B, 90C) 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 together with the coupling member (100, 140), at least a part of the core portion facing an inner side of the coil portion; the coupling member (100, 140) is formed integrally with the core portion; and a recessed portion (103, 133c) is formed in one of the receiving member (33, 133) and the coupling member (100, 140), a protruding portion (33c, 143) facing the recessed portion (103, 133c) is formed in the other one of the receiving member (33, 133) and the coupling member (100, 140), and the receiving member (33, 133) and the coupling member (100, 140) are coupled to each other via the recessed portion (103, 133c) and the protruding portion. the sensor (90, 90A, 90B, 90C) 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 together with the coupling member (100, 140), 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 together with the coupling member (100, 140), at least a part of the core portion facing an inner side of the coil portion; the coupling member (100, 140) is formed integrally with the core portion; and a recessed portion (103, 133c) is formed in one of the receiving member (33, 133) and the coupling member (100, 140), a protruding portion (33c, 143) facing the recessed portion (103, 133c) is formed in the other one of the receiving member (33, 133) and the coupling member (100, 140), and the receiving member (33, 133) and the coupling member (100, 140) are coupled to each other via the recessed portion (103, 133c) and the protruding portion.