This operation input device is an operation input device for inputting an operating command to a manipulator for observing or treating an affected area. Provided is an operation input device including: a grip gripped by an operator with his/her hand and an arm for movably supporting this grip, wherein this arm includes at least two link members, and at least one joint for linking a neighboring pair of the link members tiltably about joint axes intersecting the longitudinal axes thereof, and each of the joints 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.
