Kinetic insight into supramolecular polymerization allows for the control over self-assembled nanostructures. For example, we have recently achieved living supramolecular polymerization, which enabled us to synthesize supramolecular polymers with controlled length and narrow polydispersity.[1,2] This method is expected to lead to the synthesis of supramolecular block copolymers, yet doing so remains a great challenge. Herein, supramolecular copolymerization of two different porphyrin derivatives complexed with either zinc or copper (1T_Zn or 1T_Cu, respectively) as metal core was investigated. These two different porpyrins can coassemble because of their structural similarity. Through the seeded-growth approach, which we have previously established[1,2], we succeeded in the extension of the block of 1T_Cu stack from the 1T_Zn seed, thereby creating the supramolecular block copolymer (1T_Cu-1T_Zn-1T_Cu) Interestingly, the end-capped supramolecular block copolymer (1T_Cu-1T_Zn-1TCu) showed the enhanced kinetic stability in comparison with non-protected supramolecular polymer at terminal part (1T_Zn-1T_Zn-1T_Zn) against axial ligand (DMAP). We believe that this approach will expand the understanding on kinetic insight and potential application of supramolecular polymerization. [1] S. Ogi, K. Sugiyasu, S. Manna, S. Samitsu, M. Takeuchi, Nat. Chem., 2014, 6, 188-195. [2] T. Fukui, S. Kawai, S. Fujinuma, Y. Matsushita, T. Yasuda, T. Sakurai, S. Seki, M. Takeuchi, K. Sugiyasu, Nat. Chem., 2017, 9, 493-499.