Provided is a stator (10) comprising: a stator core having a plurality of slots (23) and teeth (21); and a coil (30) formed by winding a flat conductor (D) and disposed in the slots (23). For the purpose of improving the lamination factor in the stator, of the corners of the rectangular cross-section of the flat conductor (D), a first corner (301) of the corners positioned on the inner peripheral side of the coil (30) when the flat conductor (D) is wound to form the coil (30) is provided with a round chamfer having a radius larger than that of another corner, and when the coil (30) is inserted into the slots (23) of stator core pieces (20), the rectangular cross-section of the coil (30) is disposed such that the first corner (301) faces toward the outer peripheral side of the stator (10).