[Problem to be solved] To allow appropriately making a structure visible depending on a distance between a view point position of a virtual endoscope and the structure. [Solution] A structure extracting unit (24) extracts a structure from a three-dimensional medical image (M), and a view point determining unit (26) determines a view point position and a direction of line of sight of a virtual endoscopic image. An image generating unit (27) calculates a distance between the view point position (P1) and the extracted structure, changes an opacity defined in a color template depending on the distance, and generates, from the three-dimensional medical image (M), a virtual endoscopic image containing the structure shown according to the color template with the changed opacity viewed from the view point position (P1) in the direction of line of sight (VI). A display control unit (28) displays the thus generated virtual endoscopic image (GO) on a WS display (10).
