Abstract: A rotary damper having a cylinder (10) with a partition wall (13); a rotor (20) having a shaft portion (21) opposing the partition wall; a first recess (16) formed on a distal end surface of the partition wall; an elastic body (40) installed in the first recess and closely contacting the shaft portion to seal a gap between the partition wall and the shaft portion; and a second recess (27) formed in a part of an outer peripheral surface of the shaft portion not opposing the distal end surface of the partition wall during operation, and forming a space (50) into which the elastic body can be inserted without being compressed by facing an opening of the second recess to an opening of the first recess during assembly.

Abstract: A rotary damper includes a lid (130) that closes an opening of a case (110), a protrusion (131) formed on the lid (130), and a groove (114) having an arc shape formed on the case (110). A bottom surface of the groove (114) has a gradient. The protrusion (131) moves in the groove (114) while contacting the bottom surface of the groove (114), thereby displacing the lid (130).