An object of the present invention is to provide a pretest capsule that makes it possible to check a lumen passability of a capsule medical device until when the device reaches a desired organ within a subject, and that is easily excreted from the subject after checking the lumen passability. A pretest capsule (1) according to the present invention is a lumen passability checking device that checks a lumen passability of a capsule medical device to be inserted into the body of a subject, and includes an expandable and shrinkable outer casing (2) and a shape manipulating unit (4) that manipulates a three-dimensional shape of the outer casing (2). The outer casing (2) contains a fluid (3) and the shape manipulating unit (4), and is expanded by a pressure of the contained fluid (3), thereby forming an external diameter substantially equal to that of a desired capsule medical device. The shape manipulating unit (4) flows out the fluid (3) from a communication part (2b) of the outer casing (2), thereby shrink-deforming the outer casing (2). In this case, the outer casing (2) is shrink-deformed along flow of the fluid (3), while maintaining a state of being integrated with the shape manipulating unit (4).
