An ice making apparatus which includes an ice making tray to produce ice and an ejector rotatably disposed at the ice making tray, including a plurality of ice making cells formed in the ice making tray, wherein each of the ice making cells includes a freezing portion in which ice is produced and a buffering portion which is formed as a specified space at one side of the freezing portion to prevent water of the freezing portion from flowing out of the ice making tray. Accordingly, even in a refrigerator having the ice making apparatus installed on a rear surface of the door, the ice making apparatus can permanently provide an effect of preventing water inside the ice making cells from flowing out of the ice making tray due to an opening/closing operation of the door.