A method of starting an electric brushless rotating machine for driving an internal combustion engine which has a magnetic rotor joined to an output shaft of the internal combustion engine and a set of stator windings of a first phase, a second phase, and a third phase arranged at equal phase intervals of an electric angle of 120 degrees so that the stator windings are energized in a sequence for forced commutation according to a rotating position detecting signal from the rotor, comprising the steps of: carrying out an initial magnetization comprising a first initial magnetization step and a second initial magnetization step for initial magnetization at the startup to hold the magnetic rotor at a position, wherein it is determined that the magnetic rotor stops at the position when the counter electromotive force is zero, said first and second initial magnetization steps (S1, S2) being different in the energizing phase; carrying out the forced commutation to energize the windings of the phases in a sequence while gradually increasing the level of the energization for forcefully rotating the magnet rotor; and generating the rotating position detecting signal from a voltage signal induced on the not-energized windings during the forced commutation and carrying out a normal action of the energization based on the rotating position detecting signal thus allowing the magnetic rotor to drive the output shaft of the internal combustion engine, and canceling the energization when the number of revolutions or the full turning motion in the internal combustion engine determined from the rotating position detecting signal reaches a predetermined level or times, wherein the duty cycle of PWM during the energization after the completion of the initial magnetization is gradually increased with a limiter arranged for limiting the energizing current to a specific level, wherein, when the energizing current reaches the specific level, the energizing current is continuously supplied at the specific level during forced cummutation. carrying out an initial magnetization comprising a first initial magnetization step and a second initial magnetization step for initial magnetization at the startup to hold the magnetic rotor at a position, wherein it is determined that the magnetic rotor stops at the position when the counter electromotive force is zero, said first and second initial magnetization steps (S1, S2) being different in the energizing phase; carrying out the forced commutation to energize the windings of the phases in a sequence while gradually increasing the level of the energization for forcefully rotating the magnet rotor; and generating the rotating position detecting signal from a voltage signal induced on the not-energized windings during the forced commutation and carrying out a normal action of the energization based on the rotating position detecting signal thus allowing the magnetic rotor to drive the output shaft of the internal combustion engine, and canceling the energization when the number of revolutions or the full turning motion in the internal combustion engine determined from the rotating position detecting signal reaches a predetermined level or times, wherein the duty cycle of PWM during the energization after the completion of the initial magnetization is gradually increased with a limiter arranged for limiting the energizing current to a specific level, wherein, when the energizing current reaches the specific level, the energizing current is continuously supplied at the specific level during forced cummutation.