Abstract: An incubator comprises an incubating chamber for accommodating an infant, and air supply means for supplying conditioned air into the incubating chamber. The air supply means comprises a dry passage and a wet passage which are partitioned from each other by a partition wall. The dry passage and the wet passage communicate by means of a first opening and a second opening, respectively, with the incubating chamber. The wet passage communicates by means of a connecting passage having an opening formed in a wall of the dry passage extending along the direction of air flow through the dry passage with the dry passage. A water tank containing water for humidifying air is provided in the connecting passage. A restricting means is provided at least for the first opening to regulate the flow rate of air that flows through the first opening.