The rotary damper includes a brake drum (10) whose either end is integrally connected to the first member (100); a cylindrical case (20) covering the brake drum (10) in a state that the cylindrical case relatively rotates with respect to the brake drum, and being connected to the second member (200) in a state that the cylindrical case rotates in conjugation with the second member; a brake spring (30) being externally fitted to the brake drum (10) with the coil spring tightened, and being configured by a coil spring whose one end is fixed to one end of the cylindrical case (20) and other end is fixed to other end of the cylindrical case. The brake drum (10) is provided with a releasing concave portion (10c) on an outer periphery thereof and fixing portions for winding the brake spring rotating independently from the brake drum.