PROBLEM TO BE SOLVED: To easily observe the state of a corresponding position in another virtual endoscopic image when a position is assigned in one virtual endoscopic image of two virtual endoscopic images visualized from three-dimensional data.SOLUTION: A virtual endoscopic image generating means 13 generates first and second virtual endoscopic images based on first and second three-dimensional data 21 and 22. A position assignment receiving means 14 receives assignment of a position on the first virtual endoscopic image. A three-dimensional position specifying means 15 specifies a three-dimensional position in the first three-dimensional data 21 corresponding to the position assigned by a user. A three-dimensional position converting means 16 converts the three-dimensional position in the first three-dimensional data 21 corresponding to the position assigned by the user to a three-dimensional position in the second three-dimensional data 22. A corresponding position visualization means 17 visualizes and displays the three-dimensional position in the second three-dimensional data 22 corresponding to the position assigned by the user.
