A dehumidification forward passage is provided for guiding air withdrawn from a treating chamber as dehumidification-subject air A″ to an adsorption area of an adsorption/desorption type dehumidifying device. A dehumidification return passage is provided for guiding air A″ past through the adsorption area to the treating chamber. A desorption heat pump is provided for heating desorbing air HA to be flown through a desorption area of adsorption/desorption type dehumidifying device, with utilizing, as a heat sink, dehumidified air A″ which has flown through the adsorption area and sent to the dehumidification return passage. There is provided a sensible-heat heat exchanger configured to cool the dehumidification-subject air A″ present in the dehumidification forward passage through a heat exchange reaction with dehumidified air A″ present in the dehumidification return passage which has been cooled via absorption of its heat by the desorption heat pump.