A suspension device, comprising: one member having a rod shape; another member into which the one member is slidably inserted; and a stroke lock section adapted to stop sliding of the one member, wherein the stroke lock section includes: a stroke lock chamber having a tubular shape and formed between an outer periphery of the one member and an inner periphery of the another member; and a pump adapted to change an internal pressure of the stroke lock chamber, characterized in that a pair of annular elastic seals (4,4) are arranged respectively on both sides of the stroke lock chamber so as to be held in slide-contact with the outer periphery of the one member and sealing both openings of the stroke lock chamber; wherein the stroke lock section is adapted to compress and deform the elastic seals (4,4) in an axial direction so as to stop sliding of the one member through the another member when the stroke lock chamber is pressurized by the pump, and is adapted to return the elastic seals (4,4) to original shapes so as to enable the one member to slide through the another member when the pressurization of the stroke lock chamber is canceled by the pump. one member having a rod shape; another member into which the one member is slidably inserted; and a stroke lock section adapted to stop sliding of the one member, wherein the stroke lock section includes: a stroke lock chamber having a tubular shape and formed between an outer periphery of the one member and an inner periphery of the another member; and a pump adapted to change an internal pressure of the stroke lock chamber, characterized in that a pair of annular elastic seals (4,4) are arranged respectively on both sides of the stroke lock chamber so as to be held in slide-contact with the outer periphery of the one member and sealing both openings of the stroke lock chamber; wherein the stroke lock section is adapted to compress and deform the elastic seals (4,4) in an axial direction so as to stop sliding of the one member through the another member when the stroke lock chamber is pressurized by the pump, and is adapted to return the elastic seals (4,4) to original shapes so as to enable the one member to slide through the another member when the pressurization of the stroke lock chamber is canceled by the pump. a stroke lock chamber having a tubular shape and formed between an outer periphery of the one member and an inner periphery of the another member; and a pump adapted to change an internal pressure of the stroke lock chamber, characterized in that a pair of annular elastic seals (4,4) are arranged respectively on both sides of the stroke lock chamber so as to be held in slide-contact with the outer periphery of the one member and sealing both openings of the stroke lock chamber; wherein the stroke lock section is adapted to compress and deform the elastic seals (4,4) in an axial direction so as to stop sliding of the one member through the another member when the stroke lock chamber is pressurized by the pump, and is adapted to return the elastic seals (4,4) to original shapes so as to enable the one member to slide through the another member when the pressurization of the stroke lock chamber is canceled by the pump.