A lumen passability checking device includes: an expandable and shrinkable outer casing that contains a predetermined fluid, is expanded by a pressure of the contained fluid, and forms an external diameter substantially equal to that of a capsule medical device to be inserted into a body of a subject and a shape manipulating unit that flows out the fluid contained in the outer casing to shrink-deform the outer casing. The outer casing is shrink-deformed by flowing out the fluid, while maintaining a state of being integrated with the shape manipulating unit.
