We study the $\Lambda_c N - \Sigma_c N$ system on the basis of the coupled-channel HAL QCD method. The potentials are extracted from Nambu-Bethe-Salpeter wave functions on the lattice, which are faithful to S-matrix in QCD. One of the advantages of this approach is that it is possible to extract the potentials without any assumptions. I will present our results of the coupled-channel potentials in the $\Lambda_c N - \Sigma_c N$ in $J^P = 1^+$ system and scattering observables such as phase shifts and mixing angles. We observe that the coupling between the $\Lambda_c N$ and $\Sigma_c N$ channel is weak and the attraction in $\Sigma_c N$ channel is stronger than that in $\Lambda_c N$ channel.