We report the increase in the magnetic critical current density () of indium added polycrystalline SmFeAsO_1-xF_x. The value of magnetic is around A/cm² at 4.2 K under a self-magnetic field. Polycrystalline SmFeAsO_1-xF_x is mainly composed of superconducting grains and a little amorphous FeAs compounds. These components randomly coexist and amorphous areas are located between superconducting grains. Therefore, superconducting current is prevented from flowing by the amorphous areas. In this study, it is found that indium addition to polycrystalline SmFeAsO_1-xF_x removes these amorphous areas and induces the clustering of the superconducting grains. This means that the total contact surface area of grains increases. We suggest that the increase in the magnetic is a direct effect of the indium addition.