A tube for a heat exchanger has notch portions at a longitudinal direction end portion to be inserted into a header tank. Further, several passage holes are provided in the tube to extend in a longitudinal direction of the tube in which refrigerant flows. The notch portions are formed by cutting parts of the tube to be defined by cut surfaces. The passage holes are not provided at portions corresponding to the cut surfaces. Therefore, the passage holes are securely prevented from being crushed and cut when the notch portions are formed by cutting. As a result, joining failure between the tube and the header tank can be prevented.