A refrigerator comprising: an outer case formed in a box shape, defining an exterior of the refrigerator; and an inner case, disposed inside the outer case, providing a storage space for storing food items, the inner case including: an upper surface portion; two side surface portions; a rear surface portion; and a lower surface portion, wherein the refrigerator further comprises a metal plate attached to an inner surface of the inner case, the metal plate including two side plates which are disposed inside the inner case, wherein the inner case includes a recessed portion formed at each of the two side surface portions, wherein the recessed portion is a portion of each of the two side surface portions that is bent outward at a position spaced apart from a front end thereof and then bent backward again, so that a respective one of the two side plates can be inserted therein, wherein the refrigerator further comprises an evaporator that is located in the inner case and that is configured to generate cool air; and a grille part which is disposed at the inner surface of the upper surface portion, wherein the side plate includes: second surface which shields an inner surface of the side surface portion; and a second front end portion which is bent backward from a front end of the second surface to be parallel to the second surface, wherein, the side plate being inserted in the recessed portion, an outer surface of the second front end portion is in contact with an inner surface of the recessed portion, characterized in that the metal plate further includes an upper plate which is coupled to an inner surface of the upper surface portion, wherein a front end of the upper plate is connected to a rear end of the grille part, wherein the refrigerator further comprises: an upper duct disposed outside of the upper surface portion and having one end communicating with the grille part; and a rear duct disposed inside of the rear surface portion to connect the evaporator and the other end of the upper duct, wherein a front end of the grille part is disposed at a position spaced apart from a front end of the upper surface portion, to discharge cold air which is generated in the evaporator to inside of the inner case, wherein the recessed portion is recessed in a depth corresponding to a width between the second front end portion and the second surface, and wherein the rear duct comprises a metallic material, and defines one or more discharge openings that are configured to discharge cool air into the storage space. an outer case formed in a box shape, defining an exterior of the refrigerator; and an inner case, disposed inside the outer case, providing a storage space for storing food items, the inner case including: an upper surface portion; two side surface portions; a rear surface portion; and a lower surface portion, an upper surface portion; two side surface portions; a rear surface portion; and a lower surface portion, wherein the refrigerator further comprises a metal plate attached to an inner surface of the inner case, the metal plate including two side plates which are disposed inside the inner case, wherein the inner case includes a recessed portion formed at each of the two side surface portions, wherein the recessed portion is a portion of each of the two side surface portions that is bent outward at a position spaced apart from a front end thereof and then bent backward again, so that a respective one of the two side plates can be inserted therein, wherein the refrigerator further comprises an evaporator that is located in the inner case and that is configured to generate cool air; and a grille part which is disposed at the inner surface of the upper surface portion, wherein the side plate includes: second surface which shields an inner surface of the side surface portion; and a second front end portion which is bent backward from a front end of the second surface to be parallel to the second surface,