An insulated cabinet comprising: a cabinet body having a peripheral wall including a ceiling wall, a bottom wall, a left sidewall and a right sidewall, wherein the cabinet body is formed with an opening in a front and having a storage compartment in an interior thereof, the storage compartment communicating with the opening; and a defining member provided in at least two of walls constituting a periphery of the opening, the defining member defining positions of the two walls, wherein the defining member includes a left reinforcing member and a right reinforcing member, wherein the right reinforcing member is provided at the right upper corner of the opening or the left lower corner of the opening and the left reinforcing member is provided at the left upper corner of the opening or the right lower corner of the opening; wherein the left and right reinforcing members each have a longitudinal reinforcing plate and a lateral reinforcing plate, the longitudinal reinforcing plate being formed into an elongated shape and extending in a longitudinal direction along a front of the respective sidewall (11c, 11d) and the lateral reinforcing plate being provided along a respective part of a front of the ceiling wall or a front of the bottom wall; wherein the longitudinal reinforcing plate and the lateral reinforcing plate are integrated together; characterized in that at least the distal ends of the longitudinal reinforcing plates are not fastened to other parts; and auxiliary reinforcing plates are provided in front ends of the right and left sidewalls and, wherein the auxiliary reinforcing plates have bent portions (62b, 62a) formed by bending right and left sides thereof rearward and the longitudinal reinforcing plates are respectively inserted between the bent portions (62a, 62b). a cabinet body having a peripheral wall including a ceiling wall, a bottom wall, a left sidewall and a right sidewall, wherein the cabinet body is formed with an opening in a front and having a storage compartment in an interior thereof, the storage compartment communicating with the opening; and a defining member provided in at least two of walls constituting a periphery of the opening, the defining member defining positions of the two walls, wherein the defining member includes a left reinforcing member and a right reinforcing member, wherein the right reinforcing member is provided at the right upper corner of the opening or the left lower corner of the opening and the left reinforcing member is provided at the left upper corner of the opening or the right lower corner of the opening; wherein the left and right reinforcing members each have a longitudinal reinforcing plate and a lateral reinforcing plate, the longitudinal reinforcing plate being formed into an elongated shape and extending in a longitudinal direction along a front of the respective sidewall (11c, 11d) and the lateral reinforcing plate being provided along a respective part of a front of the ceiling wall or a front of the bottom wall; wherein the longitudinal reinforcing plate and the lateral reinforcing plate are integrated together; characterized in that wherein the defining member includes a left reinforcing member and a right reinforcing member, wherein the right reinforcing member is provided at the right upper corner of the opening or the left lower corner of the opening and the left reinforcing member is provided at the left upper corner of the opening or the right lower corner of the opening; wherein the left and right reinforcing members each have a longitudinal reinforcing plate and a lateral reinforcing plate, the longitudinal reinforcing plate being formed into an elongated shape and extending in a longitudinal direction along a front of the respective sidewall (11c, 11d) and the lateral reinforcing plate being provided along a respective part of a front of the ceiling wall or a front of the bottom wall; wherein the longitudinal reinforcing plate and the lateral reinforcing plate are integrated together; characterized in that at least the distal ends of the longitudinal reinforcing plates are not fastened to other parts; and auxiliary reinforcing plates are provided in front ends of the right and left sidewalls and, wherein the auxiliary reinforcing plates have bent portions (62b, 62a) formed by bending right and left sides thereof rearward and the longitudinal reinforcing plates are respectively inserted between the bent portions (62a, 62b).