The purpose of this study is to calculate the moment of sharing ratio for each component of the U shaped composite beam. The experimental results show that the yield moment is 1,129.5 kN․m and the theoretical value based on the strain gages is 1,057 kN․m with a difference of about 7%. As a result, the share ratio of the slab of reinforced concrete and the bottom plate of the U shaped beam were found to be about 88%.