A head-side inflow/outflow unit (60) and a foot-side inflow/outflow unit (70), which have a respective outlet opening (61, 71) for providing a supply of conditioned air to a sleeping compartment (11) within a capsule main body (20) and a respective inlet opening (62, 72), associated with the outlet opening (61, 71), for drawing in internal air of the sleeping compartment (11), are provided. The air-conditioning capacity of conditioned air supplied through each of the outlet openings (61, 71) is controlled such that the temperature of conditioned air supplied through the outlet opening (61) of the head-side inflow/outflow unit (60) falls below the temperature of conditioned air supplied through the outlet opening (71) of the foot-side inflow/outflow unit (70). In the head-side inflow/outflow unit (60), the inlet opening (62) is situated below the outlet opening (61), while on the other hand in the foot-side inflow/outflow unit (70) the inlet opening (72) is situated above the outlet opening (71), thereby producing flow of an air current causing a short-circuit between the outlet opening (61, 71) and the inlet opening (62, 72).