Using high-resolution vector magnetograms of NOAA Active Region 10043, observed on 2002 July 26 with the Advanced Stokes Polarimeter and low-order adaptive optics system, we studied the magnetic field topology and line-of-sight velocities in two flux cancellation sites. We found that the magnetic field is near horizontal at the place where two opposite polarities cancel each other. In addition, we observed significant downflows of about 1 km s 1 near the polarity reversal line, where the field is horizontal. We interpret these observations as the direct evidence of the magnetic flux submergence of concave-down (Q-shaped) magnetic loop at the flux cancellation sites.