[en] Three dimensional toroidal MHD code 'AEOLUS-IT' has been developed, on a basis of the new reduced set of resistive MHD equations with the assumption of toroidal incompressibility instead of the tokamak ordering in the conventional reduced set of resistive MHD equations. The code can carry out an overall MHD calculation with the effect of finite plasma resistivity, linear and nonlinear, of low aspect ratio and low-q tokamak because the basic equations include the ideal m = 1 mode. The implicit time integration scheme for the linear term of the perturbation is employed, dividing the variables into the equilibrium and perturbation parts. The huge CPU time due to solution of the large matrix can be reduced by high efficiency of vectorialization. The linear calculations, an eigenvalue problem, show the linear growth rates of ideal m = 1 mode and show the comparison of the growth rates between cylindrical and toroidal configurations of low-q tokamak. The linear calculations and nonlinear simulations of resistive ballooning modes are carried out and the both results are in good agreement with those obtained by the toroidal MHD code 'AEOLUS-RT' using the conventional reduced MHD equations. The linear and nonlinear calculations of tearing mode for the numerical equilibrium are also carried out and the almost the same results are obtained as the one obtained using the analytical equilibrium of almost the same parameters. (author)