To provide a technology of reducing a difference with respect to a target position of a curvable portion of a continuum robot which is to move forward substantially along a trajectory including a branched trajectory and a space. A continuum robot includes a plurality of curvable portions separately driven by wires, and control units which control positions of a plurality of curvable portions in accordance with a kinematic model. A modification value for modifying the kinematic model based on a target position and a measured position about each of the cases in which the plurality of curvable portions take a plurality of positions having at least one intersection is calculated. Modification uses a modification result in at least one of the plurality of positions as an initial value to modify the kinematic model in another position, and synthesizes the plurality of modification values.