Abstract: A structure for locking a display case door including a door handle, a pair of support members supporting the end portions of the handle, a lower support member of which has a through hole, and a locking piece extendably and retractably below the lower support member and having a through hole capable of facing the though hole of the lower support member so that an arm of a lock can be inserted through the both through holes. Since the locking piece can be positioned below and within the lower support member, it does not become any obstruction to the customers. A structure for treating dew drops dropped from a door of a display case including a tray for catching the dropped dew drops, a dew drops scattering inhibitor plate on the front portion of the tray, and a guide path on the rear portion of the tray and sloped down toward a machine room.