An apparatus for environmental tests includes a chamber having formed therein a test space for disposing a sample, and a tray that is provided on the upper surface of the chamber and has an open upper surface. A front wall of the tray is configured by an operation unit where switches are provided. A rear wall of the tray is configured by a control unit housing a control substrate. A left wall and a right wall of the tray are configured by hollow bodies connecting the operation unit and the control unit. The tray is covered with a lid.