The hemorrhoid ligation apparatus (10) includes a main cylinder (12) to which an O-ring (50) for ligating the hemorrhoid is to be attached on an outer circumferential surface of a front end portion, a sub cylinder (14) air-tightly and slidably provided inside the main cylinder (12), so as to suck the hemorrhoid into the front end portion of the main cylinder (12) upon being drawn toward a rear end portion of the main cylinder (12), an operating fluid loaded inside the sub cylinder (14), and a plunger (16) air-tightly and slidably provided inside the sub cylinder (14), so as to pressurize the operating fluid upon being squeezed toward a front end portion of the sub cylinder (14), to thereby squeeze the O-ring (50) toward the front end portion of the main cylinder (12) with the pressurized operating fluid, thus detaching the O-ring (50) from the main cylinder (12).
