The drift model is an extention of magnetohydrodynamics (MHD) with the ion finite Larmor radius effects. It is demostrated with a one-dimensional simulation code that the dispersion relation of the kinetic Alfvén wave is reproduced with the drift model. The simulation code for MHD and energetic alpha particles (MEGA) has been extended with the drift model and an extended Ohm's law where the electron Landau damping is taken into account with the Landau fluid model. The linear stability of the alpha-particle driven Alfvén eigenmode in the Tokamak Fusion Test Reactor (TFTR) deuterium-tritium (D-T) plasma was investigated with the extended MEGA code. The nonlinear simulation results of an ITER-like plasma with a weak negative shear are presented.