The present invention provides an ice making device for a refrigerator, which is installed in a storage space of the refrigerator to make ice by cold air circulating through the storage space. The ice making device comprises a water tank which is installed within an ice making space provided in a receiving box installed to be introduced into and taken out from the storage space, and has a water-storing space for storing water to be used in making ice and at least one water-supplying hole for use in supplying the water stored in the water-storing space； and at least one ice tray installed in the ice making space and provided with at least one ice making recess for use in making ice by receiving the water stored in the water-storing space. The water stored in the water tank is supplied to the ice tray when the water tank is mounted in the storage space.
