To prevent dropwise condensation from occurring to a possible extent in the surrounding of the device do to exhaust air.

A steam processing unit 44 is disposed in the exterior of an exhaust opening 40 leading to the exhaust opening 40 to exhaust air from a washing tub 11. The steam processing unit 44 has a case 45 having an air passage 46, a cooler 47, a dew receiver 48, and a dew guiding pipe 49. Air exhausted from the exhaust opening 40 is cooled by the cooling section 47a of the cooler 47 during passage through the air passage 46, moisture contained in the exhaust air condenses in the case 45, is received by the drop receiver 48 and then guided to a sink, for example, by the pipe 49 and is treated. Therefore, air having relatively lower humidity is exhausted from the air passage 46.