Stator core and electrical motor

This invention provides a stator core 1 comprising: a core back portion 4 which has a cylindrical shape; and a plurality of tooth portions 3 which protrude from the inner surface of the core back portion 4 toward the central axis C of the cylindrical shape, and extend along the central axis C direction; wherein the core back portion 4 is dividable by a divisional plane 7 extending in the central axis C direction, and on both sides of an outer surface of the core back portion 4 which is divided by the divisional plane 7 is formed with welding portions 8 extending along the central axis C direction while protruding outward and contact with each other, a contact surface 9 of each of the welding portions 8 has a wavy shape extending along the center axis C direction, and the wavy shapes engage with each other.