A stator for a rotating electrical machine includes a stator core, two insulators, and conductive wires forming coils. At least one of the insulators includes guide grooves and through-grooves. The through-grooves include at least two first grooves each of which divides at least two of the guide grooves. Each of the first grooves has a recess that is recessed in the circumferential direction with respect to the rest of the first groove at a portion that divides one of the at least two guide grooves divided by the first groove. The conductive wires extending through the corresponding through-grooves and outward in the radial direction of the insulator base are guided in the circumferential direction by the corresponding guide grooves. The conductive wires extend through the recesses in the corresponding first grooves.