Specification of a point of interest is received. After then, a distance of movement on a path from an initial viewpoint is obtained based on an operation amount obtained at an operation unit, such as a mouse. View line vectors are set by sequentially changing the view line vectors from an initial view line vector with its start point located at the initial viewpoint to a shortest view line vector connecting a point of interest and a viewpoint at a shortest distance by moving, along the path, a viewpoint of a virtual endoscope on the path from the initial viewpoint closer to the point of interest and by changing the direction of a view line of the virtual endoscope closer to a direction toward the point of interest. Virtual endoscopic images are sequentially generated based on the set view line vectors, and the generated virtual endoscopic images are sequentially displayed.