A refrigerator includes a main body including a plurality of wall modules, a storeroom disposed inside the main body, and a door arranged to open or close the storeroom. The plurality of wall modules include a first wall module having a concave portion and a second wall module having a convex portion engaged with the concave portion. The convex portion includes an insulation filling space in which insulation is filled, and a fastening groove. A fastening member is inserted into the fastening groove so as to be fastened to the first wall module and the second wall module.