Polarization observations are a current trend of the Atacama Large Millimeter/submillimeter Array (ALMA), which trace magnetic fields or other phenomena around protostars. My previous ALMA observations suggested that magnetic fields with a strength of ~2 mG could result in an infall motion at ~30% of the free fall velocity in the envelope of the Class I protostellar system TMC-1A. To verify this strength, we observed TMC-1A in polarized continuum emission at 1.3 mm using the Submillimeter Array (SMA) and ALMA at ~400 and ~40 au resolutions, respectively. We verified the mG strength by applying the Davis-Chandrasekhar-Fermi method to the SMA result. The ALMA observations detected polarized emission in the central 100-au region and in the outflow direction (north and south). The central component shows polarization directions in the disk-minor axis over ~100 au, suggesting self-scattering on the disk. The northern and southern components also show the polarization direction in the disk-minor direction, which can be explained by toroidal magnetic fields.