Prototype cavity BPMs for ATF2 Q-magnets were fabricated. We describe the results of the port measurement. f, QL, Q0, Qext and were checked. Qext was a little higher than the design, but it seems to be acceptable. A ne tuning of the cavity diameter is needed to adjust the frequency to be 6.426 GHz. It was found that the frequency changes a little and x-y isolation becomes worse, after brazing. E ectiveness of the frequency splitting dents was not clear, especially after brazing.