The distribution of magnetic field in the container is important for the polishing ability of a permanent magnet-type magnetic barrel finishing machine. Therefore, in this study, the magnetic field distribution was measured with different magnets arrangement. It is found that the polarity and strength of magnets on a magnet block greatly affect the distribution of magnetic field. Polishing experiments were done to investigate the polishing ability. The relationship between the magnetic field distribution and the polishing ability was discussed. As a result, it was concluded that strong magnetic field led to superior polishing ability.