When a predetermined range of a bend member is divided into a plurality of segments which neighbor in order in a longitudinal direction and are estimation units each having at least information of a length, a curvature and a direction for estimating a bend shape of the bend member, a shape estimation unit includes a segment shape estimation unit which estimates a shape of each of the segments by using segment information including at least one piece of curvature information with respect to each segment, and a bend member shape estimation unit which estimates the bend shape in the predetermined range by connecting end portions of each two neighboring segments, such that tangent directions of end portions of the shapes of the two neighboring segments coincide and directions around the tangent directions coincide.
