Title Study of role of tensor correlation in light nuclei based on the tensor-optimized shell model Abstract We investigate the role of the tensor correlation in light nuclei. Recently, we have developed the method to optimize the tensor force contribution in nuclei based on the new shell model method, called as "tensor-optimized shell model(TOSM)". We apply TOSM to clarify the structures of light nuclei, such as the LS splitting phenomena, and the magic number breaking in neutron halo nuclei. The short-range correlation is simultaneously treated using the unitary correlation operator method (UCOM). We show the results of the cobmined TOSM+UCOM framework using the bare interaction.