PROBLEM TO BE SOLVED: To more naturally represent a biological tissue included in a three-dimensional space as a three-dimensional image.SOLUTION: A plurality of threshold values are applied to volume data, and the volume data are performed with binarization processing by use of the respective threshold values. Thereby, a plurality of pieces of three-dimensional shape data 32, 34, 36 are generated. To them, by setting a view line 38 and performing rendering processing, the three-dimensional image is generated. In a surface layer portion of the biological tissue, an imaging range of a hard portion is narrowed, while an imaging range of a soft portion is widened. Thereby, the biological tissue can be more naturally represented.
