A damper includes a piston provided with a rod, and a housing storing the piston, and generates a braking force by an operation of the piston. The piston is provided with a seal member relative to an inner wall of the housing; and a slider provided slidably relative to the piston, and contacting the inner wall of the housing with a predetermined frictional force. When the braking force is generated, the slider presses against the seal member, and a portion contacting the inner wall of the housing in the seal member deforms outwardly toward the housing.