A seat air conditioner includes a housing disposed in a space formed below a seating portion of a seat and above a cabin floor surface inside a cabin. The housing houses: a compressor that compresses and discharges a refrigerant; a condenser that dissipates heat from the refrigerant discharged from the compressor; a decompressor that decompresses the refrigerant flowing out of the condenser; an evaporator that evaporates the refrigerant decompressed by the decompressor; and an air blower that blows air to be heat-exchanged with the refrigerant. The air blower is capable of drawing the air through a ventilation opening formed on an upper face of the housing.