A refrigerator includes a cabinet defining a storage space, a main door for opening and closing the cabinet, the main door defining an opening part that is in communication with the storage space, a sub-door rotatably mounted on the main door and configured to open and close the opening part, a panel assembly forming a front surface of the sub-door and made of a half glass material, a detection device provided to the sub-door and configured to detect a user's operation, and a door lighting unit provided to the main door and configured to, based on the sub-door being closed, turn on and off according to a signal from the detection device to allow selective viewing of an inside of the opening part through the panel assembly.