The present invention provides a chemiluminescence measuring apparatus which is small in size and high in operability and has a function of performing accurate quantitative analysis and the like. The apparatus includes at least a box-like housing having an opening, a cover provided on a top surface of the housing and having a through hole for introducing a first detachable vessel into the inner space of the housing, a holder having a concave portion and enclosing the opening of the housing, the hollow chamber having an opening at a side wall thereof and partially housing a second vessel, a photo-sensing unit for detecting luminescence from the second vessel via the through hole of the hollow chamber, and a shutter mechanism for intermittently cutting optical path between the photo-sensing unit and the second vessel. Particularly, the shutter mechanism includes a rotatable hollow chamber partially housing the vessel, provided in the hollow chamber and having an opening at a side wall thereof, and a driving motor rotating the rotatable hollow chamber.