A suspension device configured to couple a handlebar and a wheel of a vehicle to each other and comprising a pair of suspensions , wherein one suspension of the pair of suspensions contains a damping mechanism and the other suspension of the pair of suspensions contains a suspension spring, the pair of suspensions each comprising: a body-side member that has a tubular shape and is located on a body side; a wheel-side member that has a tubular shape and is located on a wheel side and coupled to the body-side member , the wheel-side member being configured to move relative to the body-side member in an axial direction of the body-side member ; a cylinder of a hollow cylindrical shape that is disposed inside of the body-side member and the wheel-side member and comprises a weak portion in the axial direction on an outer side ofthe cylinder ; a rod member that is located inside of the body-side member and the wheel-side member and configured to move relatively in an axial direction of the cylinder in accordance with movement of the body-side member and the wheel-side member ; and a first defining member that is secured to an end portion of the rod member and disposed in contact with the cylinder movably in the axial direction of the cylinder , the first defining member being configured to define space in the cylinder , wherein the weak portion of the cylinder is in a position where the cylinder comprises a smaller outer diameter than end portions of the cylinder , wherein the cylinders of the pair of suspensions 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 for holding the cylinder . a body-side member that has a tubular shape and is located on a body side; a wheel-side member that has a tubular shape and is located on a wheel side and coupled to the body-side member , the wheel-side member being configured to move relative to the body-side member in an axial direction of the body-side member ; a cylinder of a hollow cylindrical shape that is disposed inside of the body-side member and the wheel-side member and comprises a weak portion in the axial direction on an outer side ofthe cylinder ; a rod member that is located inside of the body-side member and the wheel-side member and configured to move relatively in an axial direction of the cylinder in accordance with movement of the body-side member and the wheel-side member ; and a first defining member that is secured to an end portion of the rod member and disposed in contact with the cylinder movably in the axial direction of the cylinder , the first defining member being configured to define space in the cylinder , wherein the weak portion of the cylinder is in a position where the cylinder comprises a smaller outer diameter than end portions of the cylinder , wherein the cylinders of the pair of suspensions 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 for holding the cylinder . <EOS>