A heat exchanger 1 includes a pair of tanks 2 and 3 arranged a certain distance apart from each other, a plurality of tubes 4a whose both end portions are connected with the pair of tanks 2 and 3, a long receiver tank 5 arranged along and adjacently to the tank 3 and communicatably connected with the tank 3, and a reception member 20 contained in the receiver tank 5. An upper opening end portion 13b has an opening portion at one side in a longitudinal direction of the receiver tank 5 and having a reduced diameter, and a block member 15 blocks the upper opening end portion 13b. An entire of the heat exchanger 1 except the reception member 20 and the block member 15 are integrally formed by a brazing process. The reception member 20 is inserted through the upper opening end portion 13b and arranged in the receiver tank 5 after the brazing process, and then the block member 15 is joined by brazing with the upper opening end portion 13b after the reception member 20 is inserted and arranged therein.