[en] Heating a plasma up to the equilibrium state was studied with a zero-dimensional model. The pseudoclassical scaling-law is applied in the low energy temperature region below several keV and the trapped-ion scaling-law in the higher region. In the equilibrium state, the ion temperature T sub(i) and the electron density n sub(e) are 15 keV and 1.08 x 10²⁰m^-3, respectively. In the initial state, T sub(i) and n sub(e) are 1 keV and 3.3 x 10¹⁹m^-3. The startup process is treated by dividing it into 4 steps in order to minimize the heating power required to heat the plasma up to the equilibrium state in 20 sec. The heating power is 40 MW of neutral beam injection power. In the first steps, n sub(e) is kept at 3.3 x 10¹⁹m^-3 while T sub(i) is raised from 1 keV to 7 keV. In the second step, T sub(i) is kept at 7 keV while n sub(e) is increased from 3.3 x 10¹⁹m^-3 to 8.8 x 10¹⁹m^-3. In the third step, n sub(e) is kept at 8.8 x 10¹⁹m^-3 while T sub(i) is raised from 7 keV to 10.3 keV. The final step is self-sustaining, where T sub(i) is raised from 10.3 keV to 15 keV and n sub(e) is increased from 0.88 x 10¹⁹m^-3 to 1.08 x 10²⁰m^-3. (auth.)