A slewing bearing assembly effective to suppress additional expenses such as a mold cost and to resolve the problem associated with insufficient strength brought about by voids and, also, a rotation section support apparatus for a wind powered turbine are provided. The slewing bearing assembly includes inner and outer rings having raceway grooves, and a plurality of balls interposed between the raceway grooves, and a spacer interposed between the neighboring balls. This slewing bearing assembly is a four point contact ball bearing, in which respective sectional shapes of the raceway grooves are so shaped as to represent shapes in which each balls contacts inner surfaces of the raceway grooves in the inner and outer rings at four points. The spacer is made of a resinous material having a melt viscosity within the range of 1000 to 2000 Pa·s at a temperature of 270° C.