To provide an operative mechanism for easy excretion on a face up position, which prevents skin fit or the like caused by feces soiling or the like.

The operative mechanism for excretion includes a pair of operative for excretion parts 30 A and 30B, each of which is arranged abutting on each of a pair of flesh parts D1 and D2 of the hip D of a human body on the face up position so as to form an excretion space S engaged on an anus K of the human body on the face up position when the operative for excretion parts 30A and 30B open each other so as to integrally open the pair of flesh parts D1 and D2.