When acquiring a navigation image, to make it possible to set conditions the same as conditions under which a navigation image is acquired last time and create a natural navigation image. A navigation-image acquiring section controls a placement-table control section on the basis of designation of addition of a region to a navigation image and, when present imaging conditions are different from the last imaging conditions, changes the imaging conditions to the last imaging conditions, acquires a region to be added with an imaging element, and causes a display section to display an image of the acquired region to be added and an existing navigation image.