A heat exchanger has a plurality of tubes and tank portions formed by a plurality of first thin plates laminated and connected to each other, and a plurality of covering members formed by a plurality of second thin plates laminated and connected to each other. The covering members cover the tubes and the tank portions while forming a plurality of openings therebetween. Each of the first thin plates has a communication hole so that each of the openings communicates with each other. An electromagnetic valve is disposed in the heat exchanger to control a communication between the opening and an outer space of the heat exchanger. Thus, when any one of the tubes and the tank portions cracks and leaks refrigerant flowing therethrough, refrigerant is collected into the openings and is accurately rapidly discharged to the outer space by an opening operation of the electromagnetic valve.