A core part includes plural plates stacked with a gap therebetween so as to form plural refrigerant passages and plural cooling water passages. The refrigerant passages are communicated with each other in a stacking direction of the plates by a refrigerant inlet tank section and a refrigerant outlet tank section distanced from each other. A refrigerant inlet and a refrigerant outlet communicate with the refrigerant inlet tank section and the refrigerant outlet tank section, respectively, and are provided at one end of the core part in the stacking direction. The refrigerant inlet and the refrigerant inlet tank section are communicated with each other by a refrigerant inlet passage. A distance between a center of the refrigerant outlet tank section and a center of the refrigerant outlet is shorter than a distance between a center of the refrigerant inlet tank section and a center of the refrigerant inlet.