A plurality of heat exchange units (12) are placed in a frame (38). Respective heat exchange units (12) are positioned by pin holes (30) formed in fixing plates (21) installed on the heat exchange units (12) and knock pins (29) formed on a pair of bars (22) of the frame (38). The one side tank water inlet/outlet ports (19) and the other side tank water inlet/outlet ports (20) of the heat exchange units (12) are connected to the one side water receiving ports (35) of an upper tank (17) and the other side water receiving ports (36) of a lower tank (18), respectively. The upper tank (17), the heat exchange units (12), and the lower tank (18) are fixed to the frame (38) to form the heat exchanger (11). Thus, the heat exchanger having a specified heat exchange capacity and firmly supportable on a base can be provided.