A refrigerator comprising: a heat insulated box formed by an inner box, an outer box and a foam heat insulator filled between the inner box and the outer box; a drawer type storage room, a rail device, which is formed in an elongated shape, which has a first rail, a second rail and a third rail, which support a storage container so as to be movable forward and backward and which is provided within the storage room, wherein the rail device is provided with a collapsing prevention portion of the rail device, and supports the storage container to the third rail so as to be slidable forward and backward, wherein the second rail has flanges protruding right and left in upper and lower sides in a longitudinal direction, wherein the first rail is fixed to an inner surface of the inner box and movably holds a slidable member while having flanges provided so as to extend to a height going beyond the lower flange of the second rail in right and left sides in a longitudinal direction, and wherein the third rail is held so as to move the upper flange of the second rail via a slidable member, characterized in that an auxiliary member for fixing the rail device to the inner box is provided in an opposite side to the rail device while holding the inner surface therebetween, wherein the collapsing prevention portion of the rail device is configured such that the auxiliary member is arranged in a thermal insulating device side of the inner box to which the rail device is attached, and the collapsing prevention portion has a flange part extended at least to a center position of a lower surface of the first rail, and wherein the auxiliary member has a vertical flange part extending in the same direction as a direction of a force applied to the rail device at a time when the drawer door is drawn out, in a bottom surface side of the rail device. a heat insulated box formed by an inner box, an outer box and a foam heat insulator filled between the inner box and the outer box; a drawer type storage room, a rail device, which is formed in an elongated shape, which has a first rail, a second rail and a third rail, which support a storage container so as to be movable forward and backward and which is provided within the storage room, wherein the rail device is provided with a collapsing prevention portion of the rail device, and supports the storage container to the third rail so as to be slidable forward and backward, wherein the second rail has flanges protruding right and left in upper and lower sides in a longitudinal direction, wherein the first rail is fixed to an inner surface of the inner box and movably holds a slidable member while having flanges provided so as to extend to a height going beyond the lower flange of the second rail in right and left sides in a longitudinal direction, and wherein the third rail is held so as to move the upper flange of the second rail via a slidable member, characterized in that an auxiliary member for fixing the rail device to the inner box is provided in an opposite side to the rail device while holding the inner surface therebetween, wherein the collapsing prevention portion of the rail device is configured such that the auxiliary member is arranged in a thermal insulating device side of the inner box to which the rail device is attached, and the collapsing prevention portion has a flange part extended at least to a center position of a lower surface of the first rail, and wherein the auxiliary member has a vertical flange part extending in the same direction as a direction of a force applied to the rail device at a time when the drawer door is drawn out, in a bottom surface side of the rail device.