Tearing mode instability in the presence of microscopic turbulence is inves
tigated. The effects of microscopic turbulence on global MHD mode are taken
as drags which are calculated by one-point renormalization method and mean
-field approximation. These effects are reduced to effective ion viscosity,
resistivity and thermal conductivity in reduced MHD equations. Using these
equations, the stability analyses of the tearing mode are performed. It is
shown that a finite amplitude of fluctuation enhances the growth rate of t
earing mode. For very high values of turbulent diffusivities, marginally st
able state exists. The effects of each turbulent diffusivity on mode stabil
ity are examined near marginal stability boundary. Parameter dependence on
the growth rate of tearing mode is analyzed with/without the microscopic tu
rbulence. For the microscopic turbulence, a resistive ballooning mode (RBM)
turbulence and ion temperature gradient (ITG) turbulence are considered as
examples.