  We study effects of SUSY particle decouplings on a quasi fixed point (QFP) of
Yukawa coupling. From renormalization group analysis it is shown that if the
SUSY breaking scale $M_S$ is large ($\simg 1$TeV), effects of decoupling of
Higgsinos and squarks raise the top Yukawa QFP. This tendency is enhanced in
most cases of non-universal SUSY breaking. For the case of $M_S\siml 1$TeV, the
decoupling of gluinos lowers $m_t^{\rm QFP}$. We checked some parameter
dependencies for the top Yukawa QFP. The bottom-top Yukawa unified case is also
studied. When top quark mass is measured more precisely, some patterns of soft
mass spectra could be excluded if rather large initial top Yukawa coupling is
realized by underlying theory.
