A refrigerator includes a storage chamber; an evaporator; an evaporator receiving portion and a defrost water tray slantingly arranged at a lower side of the evaporator receiving portion; a machinery chamber having an evaporation tray; an upper hose communicated with the defrost water tray; a lower hose connected to the upper hose while extending to the evaporation tray, the lower hose being provided, at one side thereof, with an air inlet hole to introduce outside air. The air inlet hole is formed at a slanted mounting surface protruding inside of a vertically-extending portion of the lower hose while being slanted downward. An opening and closing unit is provided in the vertically-extending portion of the lower hose that is configured to open the air inlet hole by an internal pressure of the storage chamber during opening of the door, and to close the air inlet hole by gravity.