Abstract: A substrate processing apparatus comprising a process tube for enclosing a plurality of semiconductor wafers, injectors for introducing process gas into the process tube, a vacuum pump for exhausting the process tube, RF electrodes arranged along the outer circumference of the process tube and serving to generate high frequency electric field, when power is supplied, in a process-gas-introduced region so as to make process gas into plasmas, a high frequency power source for supplying power to the RF electrodes, heaters arranged in the process tube to directly heat the plural wafers, a power supply for supplying power to the heaters, and a controller for controlling the amount of power supplied from the power supply to the heaters.