To provide a tank casing for a receiver tank to facilitate working of a receiver tank and increase the degree of freedom in formation of a communication passage and the degree of freedom in mounting of the receiver tank.

A drum body wall part 30 a plate 29 of which is rounded and joining margin parts 31 on both sides continued to the drum body wall part 30 are formed. The joining margin parts 31 are brought into abutment against each other and a tank drum body 32 is composed of the drum body wall part 30 and the opening end of the tank drum body 32 is closed with cover bodies 33 and 34. Communication passages 35 and 36 for inflow and outflow of a refrigerant are formed with a gap provided between the joining margin parts. By forming a receiver tank 2 through press molding of a plate 29, there is no need to separately form the communication passages 35 and 36 of the receiver tank 2 by using a different member and the shapes of the communication passages 35 and 36 are also freely varied according to working of the plate.