A shock absorber is provided with: a cylinder (1); a piston rod (2); a piston (3); a rod-side chamber (10) and a piston-side chamber (11), which are separated within the cylinder (1) by the piston (3); an outer cylinder (4) which is disposed on the outer periphery of the cylinder (1) and which forms a cylindrical gap (12) between the outer cylinder (4) and the cylinder (1) to form a double-cylinder structure; a tank (5) which is mounted externally to the outer cylinder (4); a reservoir (R) which is formed within the tank (5); a piston passage (L1) which only permits the flow of hydraulic fluid flowing from the piston-side chamber (11) to the rod-side chamber (10); a suction passage (L2) which only permits the flow of hydraulic fluid flowing from the reservoir (R) to the piston-side chamber (11); a discharge passage (L3) which connects the rod-side chamber (10) and the reservoir (R); a damping valve (V3) which is provided in the discharge passage (L3); and a connection member (RH) which connects the outer cylinder (4) and the tank (5). The discharge passage (L3) communicates with the reservoir (R) through the cylindrical gap (12) and the connection member (RH).
