A load lock apparatus having a load lock chamber, which is connected to a vacuum transfer chamber configured to transfer a substrate under a vacuum pressure state via a communication hole which is opened and closed by a gate valve, and configured to be capable of switching an inner pressure into an atmospheric pressure state and the vacuum pressure state, is provided. The load lock apparatus includes a load lock chamber main body in which a substrate container having an attachable/detachable cover is carried, wherein the communication hole is formed in a side surface of the load lock chamber; and a cover attaching/detaching mechanism installed at a height position vertically arranged with the communication hole in the load lock chamber; and an elevating mechanism including a mounting table on which the substrate container is loaded and configured to lift and lower the mounting table.