The main function of an end effector is manipulated while keeping the orientation of the end effector stable, and limitations in the manipulation amount due to the movable range of the wrist are alleviated. Provided is an operation input device (2) for inputting a manipulation command to a manipulator having an end effector for observing or medically treating an affected site. The operation input device (2) includes a grip section (25) that is holdable by changing a method of holding the grip section with the same hand of an operator (0) and an operating section (16) that is provided in the grip section (25) and that is operated with a single finger, which is the same before and after the holding method is changed, so as to manipulate a main function of the end effector.
