In a rotating electrical machine, the concentrated winding coil includes a single-layer coil, corresponding to one layer, wound in a first turn advancing mode with the wire forming sequential coil turns starting from one end of the insulating bobbin toward another end of the insulating bobbin and another single-layer coil, corresponding to one layer, wound in a second turn advancing mode with the wire forming turns starting from the other end of the insulating bobbin toward the one end of the insulating bobbin, with the single-layer coil and the other single-layer coil layered alternately to each other. The insulating bobbin includes a winding portion where the concentrated winding coil is formed, collars each formed at one of two ends of the winding portion and at least one projecting portion configured to disallow misalignment at a turn changeover start area in the first and second turn advancing modes.