A stator core is formed by arranging divided cores (20) in a circumference direction in cylindrical shape. On an upper end surface (60) of a core back (50) of the divided core, holes (62, 64) are made. Then, on the upper end surface, a reinforcing ring (40) having through holes (66, 68) is arranged, and is connected with rivets (70, 72). Thus, stress is transmitted not only through a side surface(58) but also through the reinforcing ring (40), between the adjacent divided cores. Thus, strength of the stator using a powder magnetic core is ensured and a space is saved.