In a refrigerator including a sliding door configured to open and close a storage chamber, a storage basket provided on a rear portion of the sliding door, and a support frame configured to support the sliding door and the storage basket, sidewalls of the storage basket may be formed so as to protrude outwardly except a lower portion in which the support frame is disposed between an inner case and the sidewalls, thereby increasing a storage space of the storage basket. In addition, a front protrusion, an auxiliary protrusion, and a rear protrusion are formed in an upper portion of the storage basket, and therefore a relative position of an auxiliary basket to the storage basket may be limited, and the auxiliary basket may be drawn into and out in conjunction with drawn-in and-out movements of the storage basket.