A parameter value regarding an endoscope operation at an arbitrary position on a course is calculated from a three-dimensional image indicating a luminal structure. Specifically, one of a clockwise direction and a counterclockwise direction around an axis is set to positive, the other is set to negative, and a rotation angle of the endoscope due to a rotation operation at a position of a target is calculated so that a sum of a cumulative total of rotation angles of the endoscope due to a rotation operation performed until the distal end portion of the endoscope arrives at the position of the target after the distal end portion of the endoscope is inserted into a luminal structure, and the rotation angle of the endoscope due to the rotation operation at the position of the target falls within a predetermined angle range.
