A rotary electric machine includes a stacked brush, where low-resistance and high-resistance brush layers are disposed at the front and rear end sides in the rotational direction of a commutator, respectively. When the insulation gap between the neighboring segments of a commutator is “a” and the width of the high-resistance brush layer is “b”, “a” and “b” are determined to satisfy a 2×a+c, d>b, a