A chamber apparatus according to the present invention including a chamber main body including an opening portion in an upper surface; a door that opens/closes the opening portion; and a guide mechanism that slides the door with respect to the chamber main body. The door includes a movable member slidably supported by the guide mechanism; a first support provided on the movable member in a fixed manner; a door main body that opens/closes the opening portion; a second support provided on the door main body in a fixed manner; and a floating mechanism that connects the first support and the second support immovably in a horizontal direction and support the second support displaceably in a vertical direction with respect to the first support.