To provide a structure of a winding shaft for a shutter allowing high-accuracy positioning and centering work and easy and accurate assembly work of a support shaft to a shaft body.

The structure of the winding shaft for the shutter includes a winding shaft body 20 for the shutter, and a pair of support shafts 21 fixed to the center part of the shaft body 20 at both ends of the shaft body 20. The shaft body 20 includes an outer cylinder 23 serving as a winding portion of a shutter curtain 3, and an inner cylinder 25 fixed onto the center axis of the outer cylinder 23. A base part 21a of the support shaft 21 is insert-fixed into an insertion hole 25a of the inner cylinder, and a shaft part 21b of the support shaft 21 is projected from the outer surface of the inner cylinder 25. The insertion hole 25a of the inner cylinder 25 is formed in a noncircular cross section, and the outline of the base part 21a of the support shaft 21 is formed in noncircular cross-sectional shape coinciding with the insertion hole 25a.