  We investigate accurate renormalization group analyses in neutrino sector
between $\nu$-oscillation and seesaw energy scales. We consider decoupling
effects of top quark and Higgs boson on the renormalization group equations of
light neutrino mass matrix. Since the decoupling effects are given in the
standard model scale and independent of high energy physics, our method can
basically apply to any models beyond the standard model. We find that the
decoupling effects of Higgs boson are negligible, while those of top quark are
not. Particularly, the decoupling effects of top quark affect neutrino mass
eigenvalues, which are important for analyzing predictions such as mass squared
differences and neutrinoless double beta decay in an underlying theory existing
at high energy scale.
