Positioning of a pattern (30) indicating a treatment-portion (56A) on an organs surface at an appropriate position on an organ is supported. A three-dimensional image representing a patients organ is obtained, and the organ is extracted therefrom. A treatment-portion (56A), at which desirable treatment for the organ is performed, on a surface of the organ is obtained. A pattern model (30D) including an outer surface (31C), an inner surface (32A) having a surface form along an organs outer surface, a guide wall (33E) connecting, along the treatment-portion (56A), the outer surface (31C) and the inner surface (32A), and a positioning portion (34D) is generated. The positioning portion (34D) positions a predetermined imaging probe (40) in such a manner that a tomographic image of a cross-section (C) of the organ including a target-portion (A) of the organ is imageable when the guide wall (33E) is arranged along the treatment-portion (56A).
