A rotary damper is provided and includes: a housing; an annular ring member that is provided in the housing, and is made of elastomer or flexible rubber; a shaft body that is accommodated in a rotatable manner in the housing; and a sliding portion that is provided in the housing and makes contact with the ring member so as to freely slide with respect to the ring member along the circumferential direction thereof, in which: the ring member has an abutting portion that abuts the sliding portion, and a hollow portion provided inside the ring member; the hollow portion has an opening portion on the side opposite to the abutting portion; in the state of having enclosed gas in the hollow portion, the opening portion is hermetically joined to the inner surface of the housing; a projected portion that engages with the opening portion of the hollow portion is provided on the inner surface of the housing; and a pressing member that presses the ring member toward the inner surface of the housing is provided on the inner side and/or outer side of the ring member in the radial direction.