A radiator includes a tube that has a flattened-shape, the tube including an internal flow channel that allows a coolant to flow through the internal flow channel; and a tank that includes an insertion port into which a joint end portion of the tube is inserted so that the tank and the tube are joined to each other, wherein the tube includes an outer-peripheral-wall extending in a direction perpendicular to a thickness direction of the tube, and bend depressions that are bent toward the internal flow channel in a concave shape are formed in at least a region of the outer-peripheral-wall adjacent to the joint end portion, the bend depressions extending along the internal flow channel, and the bend depressions are deformed in a width direction of the tube so that the width of the joint end portion is the same as the width of the insertion port.