A insertion apparatus includes a flexible tube, a detection section that detects state information of the tube, a calculation section that calculates, based on the state information, shape information of the tube, and an input section that inputs characteristic information of the tube. The apparatus also includes a calculation section that calculates, based on the characteristic information, an operation state of a distal end of the tube, an calculation section that calculates an insertion state of the tube at a specific point closer to a proximal end than the distal end, based on the shape information, characteristic information, and operation state, and a measurement section that measures an actual operation state of the tube at the specific point.