This invention has an object of providing an air conditioner for a railway vehicle which can restrict a reduction in the introduced volume of outside air during a high-speed running of a vehicle and which can achieve lower noise. To achieve this object, the air conditioner for a railway vehicle includes an external cover 4 provided along the same surface as a vehicle surface, an air intake port 5 with a periphery provided on the external cover 4 and having a roundness in the cross-sectional configuration of an inside edge portion 12a of the intake port periphery, an air intake louver 11 disposed in the air intake port 5 to intersect a vehicle running direction, and an air exhaust port 3 for exhausting air that has been heat-exchanged, wherein an upper end surface 11a of the louver 11 is recessed from the surface of the exterior cover 4, and a cross-sectional configuration of the edge portion 11b of the upper end surface 11a has a roundness.