Rotating electrical machine and producing method of rotating electrical machine

A rotating electrical machine comprising:

• a plurality of core pieces forming a stator core, each of the core pieces comprising:
• contact surfaces along a radial direction relative to a rotation axis on one side end and another side end of the core piece in a peripheral direction around the rotation axis;
• a tapered protrusion on the contact surface of the one side end of the core piece, the protrusion comprising first inclined surfaces outside and inside in the radial direction;
• and
• a recess on the contact surface of the other side end of the core piece, the recess comprising second inclined surfaces contacting the first inclined surfaces outside and inside in the radial direction to receive the protrusion of adjacent core piece,
• a cross-sectional shape perpendicular to the rotation axis of the protrusion being a shape such that, inside a circle centered on a first end portion of one side in the radial direction of the contact surface with a distance being a radius between a second end portion on a tip side of the first inclined surface located on an opposite side of the first end portion on the protrusion and the first end portion, at least a part of the first inclined surfaces located on the opposite side of the first end portion contact the second inclined surfaces,
• wherein the cross-sectional shape of the protrusion is a shape such that a third end portion on a base end side of the first inclined surface located on an opposite side of the first end portion on the protrusion is located on circumference of the circle.