A torque adjustment function-provided rotary damper comprising: a casing that internally has a pressure chamber; a rotary member whose shaft portion is rotatably accommodated in the pressure chamber; a flange wall that is formed by closing one end portion side of the pressure chamber, that rotatably supports a tip of the shaft portion, and in which a pair of fluid passage holes (2e1,2e2,2f1,2f2) penetrating the pressure chamber and communicating with the inside and outside of the pressure chamber is formed at an interval in a circumferential direction; a viscous fluid that internally fills the pressure chamber; a valve mechanism (3e,4) that forms a large flow path of the viscous fluid around the shaft portion if the rotary member is rotated in one direction, and that applies a braking torque to the rotation of the rotary member by closing the large flow path if the rotary member is rotated in the other direction; and a torque adjustment member that is rotatably disposed in the casing by coming into contact with a surface of the flange wall opposite to the pressure chamber, and in which a groove (5a,5b) communicating with the pair of fluid passage holes (2e1,2e2,2f1,2f2) is formed on a surface to which the flange wall contacts with so that a cross-sectional area is changed in the circumferential direction, characterized in that the torque adjustment member has an adjustment end portion exposed from the casing, the rotary damper includes an operation member having an engagement portion to be linked with the torque adjustment member by engaging with the adjustment end portion, and a knob portion formed integrally with the engagement portion by protruding in a radial direction from an outer periphery side of the casing, the operation member has a guide portion to be rotatably disposed along an outer periphery of a lid that closes a casing end portion on a side opposite to a side where the adjustment end portion is exposed, or along an outer periphery of the casing at a location away from the casing end portion where the adjustment end portion is exposed, and the knob portion extends to the guide portion along an axial direction of the casing in the outer periphery of the casing. a casing that internally has a pressure chamber; a rotary member whose shaft portion is rotatably accommodated in the pressure chamber; a flange wall that is formed by closing one end portion side of the pressure chamber, that rotatably supports a tip of the shaft portion, and in which a pair of fluid passage holes (2e1,2e2,2f1,2f2) penetrating the pressure chamber and communicating with the inside and outside of the pressure chamber is formed at an interval in a circumferential direction; a viscous fluid that internally fills the pressure chamber; a valve mechanism (3e,4) that forms a large flow path of the viscous fluid around the shaft portion if the rotary member is rotated in one direction, and that applies a braking torque to the rotation of the rotary member by closing the large flow path if the rotary member is rotated in the other direction; and a torque adjustment member that is rotatably disposed in the casing by coming into contact with a surface of the flange wall opposite to the pressure chamber, and in which a groove (5a,5b) communicating with the pair of fluid passage holes (2e1,2e2,2f1,2f2) is formed on a surface to which the flange wall contacts with so that a cross-sectional area is changed in the circumferential direction, characterized in that the torque adjustment member has an adjustment end portion exposed from the casing, the rotary damper includes an operation member having an engagement portion to be linked with the torque adjustment member by engaging with the adjustment end portion, and a knob portion formed integrally with the engagement portion by protruding in a radial direction from an outer periphery side of the casing, the operation member has a guide portion to be rotatably disposed along an outer periphery of a lid that closes a casing end portion on a side opposite to a side where the adjustment end portion is exposed, or along an outer periphery of the casing at a location away from the casing end portion where the adjustment end portion is exposed, and the knob portion extends to the guide portion along an axial direction of the casing in the outer periphery of the casing.