PURPOSE: To provide a rotary damper which controls relative movement speed between two members connected relatively movable, without using oil, in a simple structure, in a small size and at a low cost.

CONSTITUTION: A rotary damper 33 is composed of a first rotor 34 rotatably fitted to a support shaft 32 which is a rotary center of an upper frame M2 from outside, a first coil spring 35 arranged between an inner peripheral surface of the rotor 34 and the support shaft 32, a second rotor 36 rotatably ritted to the first rotor 34 from outside, and a second coil spring 37 arranged between an inner peripheral surface of the rotor 36 and an outer peripheral surface of the first rotor 34. Both of the first and second coil springs are one-way springs. The first coil spring 34 is allowed to rotate in a specified direction by first torque, and prohibits the rotation in the reverse direction. The second coil spring 37 allows the second rotor 36 to rotate in a reverse direction with second torque, and prohibits the rotation in the specified direction.