Embodiments of the present invention provide a refrigerator, comprising a main body having a food storage space therein, a door installed on the main body and configured to have an ice compartment therein and close the food storage space, a compressor, a condenser, and an expansion valve that are installed in the door, an ice generator installed in the ice compartment, the ice generator comprising a tray configured to receive and contain water therein, a refrigerant pipe line configured to connect the compressor, the condenser, and the expansion valve to each other and cool the tray by conduction, and one or more lock rings configured to connect in an airtight fashion the refrigerant pipe line to the compressor, the condenser, and the expansion valve.