A tank has a tank body defining a passage therein, a plate to which tubes are attached, and an intermediate plate. The tank body has a space defining part and a tank junction part attached to the intermediate plate. A longitudinal direction and a stacking direction of the tubes are perpendicular to a width direction. The space defining part has two end parts facing each other in the width direction and connecting to two of the tank junction part respectively. The tank body has a junction end surface that has an arc shape protruding toward the passage. The intermediate plate has a part corresponding to the junction end surface and being provided with a receiving surface that has an arc shape fitting the arc shape of the junction end surface. The receiving surface is attached to the junction end surface.