  We study the implications of a vector-like quark, especially a down-type
vector-like quark in $b \rightarrow s(d) \gamma$ including the neutral Higgs in
the calculation. After analyzing some possible constraints for the mixing, the
contribution may be significant for the $b \rightarrow d \gamma$, but not for
the $b \rightarrow s \gamma$. We also find that the FCNC among ordinary quarks
vanishes for a special form of down-type quark mass matrix.
