An outdoor unit of an air conditioner comprising: a blower and a bell mouth of the blower disposed in an inner portion of a housing, wherein a top panel having an air blowing port of the blower is provided on a top surface of the housing, wherein the bell mouth includes an empty rectangular stand portion and a cylindrical body portion which is provided to protrude from the top surface of the stand portion upward and disposed to surround the outer circumference of the blower, with an upper flange formed on a top end of said cylindrical body portion, wherein the housing is provided with a basic frame, wherein the basic frame is configured including: a base panel, a left side panel and a right side panel disposed along a left side end and a right side end, respectively, of the base panel, a front beam bridged between front ends of the left and right side panels and a rear beam bridged between rear ends of the left and right side panels, wherein the front and rear beams (22F, 22R) are provided with respective supporting portions including horizontal supporting surfaces with a front face rib and a rear face rib standing substantially perpendicular from front and rear ends of the horizontal supporting surfaces, wherein the stand portion includes a front wall surface disposed on the supporting surface in the front beam side and a rear wall surface disposed on the supporting surface in the rear beam side, wherein the stand portion is fixed to the frame of the housing, characterized in that said front and rear wall surfaces (51F, 51R) comprise respective perpendicular surfaces continuing along left to right, with a center portion formed overhanging frontward from left and right wall portions (512L, 512R) via stepped surfaces, and the right and left wall portions (512L, 512R) are screwed to the rear face ribs, wherein the upper flange is disposed so as to come into contact with a circumference of the air blowing port on a back face of the top panel, and wherein a portion of a load which is applied to the top panel is supported by the bell mouth. a blower and a bell mouth of the blower disposed in an inner portion of a housing, wherein a top panel having an air blowing port of the blower is provided on a top surface of the housing, wherein the bell mouth includes an empty rectangular stand portion and a cylindrical body portion which is provided to protrude from the top surface of the stand portion upward and disposed to surround the outer circumference of the blower, with an upper flange formed on a top end of said cylindrical body portion, wherein the housing is provided with a basic frame, wherein the basic frame is configured including: a base panel, a left side panel and a right side panel disposed along a left side end and a right side end, respectively, of the base panel, a front beam bridged between front ends of the left and right side panels and a rear beam bridged between rear ends of the left and right side panels, wherein the front and rear beams (22F, 22R) are provided with respective supporting portions including horizontal supporting surfaces with a front face rib and a rear face rib standing substantially perpendicular from front and rear ends of the horizontal supporting surfaces, wherein the stand portion includes a front wall surface disposed on the supporting surface in the front beam side and a rear wall surface disposed on the supporting surface in the rear beam side, wherein the stand portion is fixed to the frame of the housing, characterized in that said front and rear wall surfaces (51F, 51R) comprise respective perpendicular surfaces continuing along left to right, with a center portion formed overhanging frontward from left and right wall portions (512L, 512R) via stepped surfaces, and the right and left wall portions (512L, 512R) are screwed to the rear face ribs, wherein the upper flange is disposed so as to come into contact with a circumference of the air blowing port on a back face of the top panel, and wherein a portion of a load which is applied to the top panel is supported by the bell mouth. a base panel, a left side panel and a right side panel disposed along a left side end and a right side end, respectively, of the base panel, a front beam bridged between front ends of the left and right side panels and a rear beam bridged between rear ends of the left and right side panels, wherein the front and rear beams (22F, 22R) are provided with respective supporting portions including horizontal supporting surfaces with a front face rib and a rear face rib standing substantially perpendicular from front and rear ends of the horizontal supporting surfaces, wherein the stand portion includes a front wall surface disposed on the supporting surface in the front beam side and a rear wall surface disposed on the supporting surface in the rear beam side, wherein the stand portion is fixed to the frame of the housing, characterized in that said front and rear wall surfaces (51F, 51R) comprise respective perpendicular surfaces continuing along left to right, with a center portion formed overhanging frontward from left and right wall portions (512L, 512R) via stepped surfaces, and the right and left wall portions (512L, 512R) are screwed to the rear face ribs, wherein the upper flange is disposed so as to come into contact with a circumference of the air blowing port on a back face of the top panel, and wherein a portion of a load which is applied to the top panel is supported by the bell mouth.