A suspension device configured to couple a handlebar and a wheel of a vehicle to each other and comprising a pair of suspensions (11A, 11B), wherein one suspension of the pair of suspensions (11A, 11B) contains a damping mechanism and the other suspension of the pair of suspensions (11A, 11B) contains a suspension spring, the pair of suspensions (11A, 11B) each comprising: a body-side member (110, 210) that has a tubular shape and is located on a body side; a wheel-side member (120, 220) that has a tubular shape and is located on a wheel side and coupled to the body-side member (110, 210), the wheel-side member (120, 220) being configured to move relative to the body-side member (110, 210) in an axial direction of the body-side member (110, 210); a cylinder (151, 311) of a hollow cylindrical shape that is disposed inside of the body-side member (110, 210) and the wheel-side member (120, 220) and comprises a weak portion in the axial direction on an outer side ofthe cylinder (151, 311); a rod member (181, 321) that is located inside of the body-side member (110, 210) and the wheel-side member (120, 220) and configured to move relatively in an axial direction of the cylinder (151, 311) in accordance with movement of the body-side member (110, 210) and the wheel-side member (120, 220); and a first defining member (182, 322) that is secured to an end portion of the rod member (181, 321) and disposed in contact with the cylinder (151, 311) movably in the axial direction of the cylinder (151, 311), the first defining member (182, 322) being configured to define space in the cylinder (151, 311), wherein the weak portion of the cylinder (151, 311) is in a position where the cylinder (151, 311) comprises a smaller outer diameter than end portions of the cylinder (151, 311), wherein the cylinders (151, 311) of the pair of suspensions (11A, 11B) comprise a uniform inner diameter and comprise the portions that have a smaller outer diameter in a same position in the axial direction, characterized in that the weak portion is disposed further on the wheel-side than a body-side cylinder holder (132, 315C) for holding the cylinder (151, 311). a body-side member (110, 210) that has a tubular shape and is located on a body side; a wheel-side member (120, 220) that has a tubular shape and is located on a wheel side and coupled to the body-side member (110, 210), the wheel-side member (120, 220) being configured to move relative to the body-side member (110, 210) in an axial direction of the body-side member (110, 210); a cylinder (151, 311) of a hollow cylindrical shape that is disposed inside of the body-side member (110, 210) and the wheel-side member (120, 220) and comprises a weak portion in the axial direction on an outer side ofthe cylinder (151, 311); a rod member (181, 321) that is located inside of the body-side member (110, 210) and the wheel-side member (120, 220) and configured to move relatively in an axial direction of the cylinder (151, 311) in accordance with movement of the body-side member (110, 210) and the wheel-side member (120, 220); and a first defining member (182, 322) that is secured to an end portion of the rod member (181, 321) and disposed in contact with the cylinder (151, 311) movably in the axial direction of the cylinder (151, 311), the first defining member (182, 322) being configured to define space in the cylinder (151, 311), wherein the weak portion of the cylinder (151, 311) is in a position where the cylinder (151, 311) comprises a smaller outer diameter than end portions of the cylinder (151, 311), wherein the cylinders (151, 311) of the pair of suspensions (11A, 11B) comprise a uniform inner diameter and comprise the portions that have a smaller outer diameter in a same position in the axial direction, characterized in that the weak portion is disposed further on the wheel-side than a body-side cylinder holder (132, 315C) for holding the cylinder (151, 311).