To provide an inexpensive heat exchanger having a reduced number of components resulting in reduced joint portions, and to provide an inexpensive exhaust gas recirculating device for an internal combustion engine using the same as an exhaust gas cooler.

The heat exchanger 53 makes heat exchange between fluid flowing in one fluid passage 62 formed in a case 61 and fluid flowing in the other fluid passage 63. The case 61 consists of a first case member 61f and a second case member 61s. The first case member 61f has fluid inlets and outlets 62a, 62b, 63a, 63b and a heat exchange chamber 64 communicated therewith. The second case member 61s has a heat exchange part 65 formed with an intermediate part 63c of the remaining fluid passage 63 and stored in the heat exchange chamber 64, and a cover part 66 formed integrally with the heat exchange part 65 and joined to the first case member 61f around the heat exchange chamber 64 in a fluid tight manner. The intermediate part of one fluid passage 62 is formed between the first case member 61f and the second case member 61s.