A support arm installation structure for a vertical axis wind wheel, in which a load and stress acting on joint sections between hubs and support arms of or joint sections between blades and the support arms of the wind wheel are dispersed to eliminate excessive stress concentration, thereby vibration and fretting corrosion etc. on the joint surfaces can be reduced. For example, the installation structure of the vertical axis wind wheel has a support arm (20) for holding blades (18) of the vertical axis wind wheel producing rotational torque and having a streamlined cross-sectional shape and has hubs (80, 81) on which support arm fixing sections (86) are radially arranged and which fix the support arms (20) by pressing them, the support arm fixing sections (86) being positioned on the rotating shaft side of a rotating body of the vertical axis wind wheel (10) and each having a section with the same shape as the outer shape of a support arm (20). |