[Problem] To provide a rotary damper wherein damping torque generated by rotation can be easily adjusted using a simple configuration. [Solution] A rotary damper 1 limits the movement of viscous fluid contained in a circular cylinder chamber 111, thereby generating damping torque against applied rotational force. This rotary damper 1 is configured such that: a lid 15 is screwed into a case 11; and the gap g1 between the lower surface 153 of the lid 15 and the upper surface 119 of a partition section 115 and the gap g2 between the lower surface 153 of the lid 15 and the upper surface 129 of a vane 122 can be adjusted by adjusting the amount of screwing of the lid 15 into the case 11. This means that adjusting the amount of movement of viscous fluid through the gaps g1, g2 can adjust damping torque generated by rotation.