Provided is a damper that prevents leakage of a liquid sealed in a cylinder and can maintain appropriate counterforce and attenuation characteristics. The piston (20) of the damper moves reciprocally, compartmentalizing the interior of a cylinder (10) into a first chamber (A) on an opening-end (11) side and a second chamber (B) on a sealed-end (12) side. The tip (31) of a piston rod (30) is joined to the piston (20) and the base (33) side protrudes to the outside from the opening end (11) of the cylinder (10). A rod guide (40) is affixed to the opening end (11) of the cylinder (10), and has a through hole (44) through which the piston rod (30) is inserted in a manner able to move in a reciprocal manner. A seal section (49) provided to the rod guide (40) is provided to a position separated at the first chamber (A) side of the greatest stroke width (S) of the piston rod (30) from the outer end (Z) of the sliding surface (47) of the through hole (44).
