A circular refrigerant outlet is formed in an endmost flat, hollow member of a laminated heat exchanger. An outlet header is fixed to the endmost flat, hollow member, and an outlet pipe having a circular cross section is connected to an open end of the outlet header. The inside diameter of the refrigerant outlet is 90% to 110% that of the outlet pipe. The outlet header has a first portion having a refrigerant passage hole communicating with the refrigerant outlet. The first portion has a vertical, flat wall portion and two fragmentary, cylindrical wall portions continuous with respective upper and lower edges of the flat wall portion. The curvature radius of the inner surface of the fragmentary, cylindrical wall portion is 35% to 50% the inside height of the first portion. The equivalent inside diameter of the first portion is 90% to 110% the inside diameter of the outlet pipe.