This operation input device is an operation input device (2) for inputting an operating command to a manipulator (3) for observing or treating an affected area. Provided is an operation input device (2) including: a grip section (25) gripped by an operator (O) with his/her hand and an arm section (22) for movably supporting this grip section (25), wherein this arm section (22) includes at least two link members, and at least one joint (J1, J2, and J3) for linking a neighboring pair of the link members tiltably about joint axes intersecting the longitudinal axes thereof, and each of the joints (J1, J2, and J3) includes: a sensor for detecting the relative angle displacement of each of the link members that are linked and a friction generation section configured to generate a frictional torque in a direction opposite to the direction in which a torque is applied.
