As a result, the inner ring gear 12a and the outer ring gear 12b will not interfere with each other when the plate spring 16 is bent.FIGS. 5A to 5D illustrates a fourth example of the hypoid gear structure according to the present invention: FIG. 5A is a plan view of the spring plate 16, FIGS. 5B and 5C are a plan view and a sectional view, respectively, of the hypoid ringgear, and FIG. 5D is a pa