A shock absorber, comprising: a shock absorber main body that absorbs a shock input to a vehicle; a gas spring chamber which is provided inside the shock absorber main body, and inside which gas is sealed, and which absorbs the shock by a gas spring that is based on the gas; an auxiliary gas spring chamber (80, 90), inside which the gas is sealed, and which communicates with the gas spring chamber, and which is formed in a cylindrical shape; a movable partition wall (82, 92) which is provided slidably in an axial direction inside the auxiliary gas spring chamber (80, 90); a gas spring chamber side gas chamber (81L, 91U) which is sectioned by the movable partition wall (82, 92) in the auxiliary gas spring chamber (80, 90) and which communicates with the gas spring chamber; and an elastic body side gas chamber (81U, 91L) which is sectioned by the movable partition wall (82, 92) in the auxiliary gas spring chamber (80, 90), and which is formed on an opposite side of the movable partition wall (82, 92) to the gas spring chamber side gas chamber (81L, 91U), and which has an elastic body having a prescribed modulus of elasticity that urges the movable partition wall (82, 92) towards the gas spring chamber side gas chamber (81L, 91U), wherein the movable partition wall (82, 92) moves towards the elastic body side gas chamber (81U, 91L) so as to increase a volume of the gas spring chamber side gas chamber (81L, 91U), as pressure inside the gas spring chamber increases, wherein the elastic body of the elastic body side gas chamber (81U, 91L) has a gas spring that is based on the gas sealed therein, characterized in that the elastic body of the elastic body side gas chamber (81U, 91L) further has a metal spring (84A, 84B), wherein an auxiliary tube is arranged in the elastic body side gas chamber (81U, 91L) and defines an initial load of the metal spring (84A, 84B). a shock absorber main body that absorbs a shock input to a vehicle; a gas spring chamber which is provided inside the shock absorber main body, and inside which gas is sealed, and which absorbs the shock by a gas spring that is based on the gas; an auxiliary gas spring chamber (80, 90), inside which the gas is sealed, and which communicates with the gas spring chamber, and which is formed in a cylindrical shape; a movable partition wall (82, 92) which is provided slidably in an axial direction inside the auxiliary gas spring chamber (80, 90); a gas spring chamber side gas chamber (81L, 91U) which is sectioned by the movable partition wall (82, 92) in the auxiliary gas spring chamber (80, 90) and which communicates with the gas spring chamber; and an elastic body side gas chamber (81U, 91L) which is sectioned by the movable partition wall (82, 92) in the auxiliary gas spring chamber (80, 90), and which is formed on an opposite side of the movable partition wall (82, 92) to the gas spring chamber side gas chamber (81L, 91U), and which has an elastic body having a prescribed modulus of elasticity that urges the movable partition wall (82, 92) towards the gas spring chamber side gas chamber (81L, 91U), wherein the movable partition wall (82, 92) moves towards the elastic body side gas chamber (81U, 91L) so as to increase a volume of the gas spring chamber side gas chamber (81L, 91U), as pressure inside the gas spring chamber increases, wherein the elastic body of the elastic body side gas chamber (81U, 91L) has a gas spring that is based on the gas sealed therein, characterized in that the elastic body of the elastic body side gas chamber (81U, 91L) further has a metal spring (84A, 84B), wherein an auxiliary tube is arranged in the elastic body side gas chamber (81U, 91L) and defines an initial load of the metal spring (84A, 84B).