A handler includes first and second cooling channels, and first and second supply channels. The first and second cooling channels correspond to housing pockets that are respectively heated by heaters. A first throttle valve controls the flow of refrigerant such that the amount of refrigerant flowing through the second cooling channel is larger than the amount of the refrigerant flowing through the first cooling channel. Temperature sensors detect the temperature of the respective housing pockets, and a control device controls the valve and the heaters so that a target temperature is maintained.