To provide a flat winding shaft and a pole plate winding device which facilitates taking-out of a wound body after completion of winding from the winding shaft and is capable of manufacturing the flat wound body continuously.

This device is provided with a winding shaft body 21 consisting of two plat plates which is split into two divisions in a cross direction, whose one end in a longitudinal direction is formed so as to be fittable in a receiving part 22 supporting the winding shaft body 21, and whose other end in the longitudinal direction is connected to a rotating shaft 29 so that the winding shaft body 21 and the other end part may be formed so as to be separated, and a clearance formation member formed on the receiving part is inserted between the two flat plates of the winding shaft body so as to form a clearance between the flat plates with the winding shaft body 21 fitted to the receiving part 22.