K-Ar dating on schistose sericite-quartz rocks which are hosts of ore deposits in the Taro mine show 123×10⁶, 126×10⁶ and 127×10⁶ years. As compared these obtained ages with K-Ar ages on surrounding granitic rocks (112×10⁶ years for Miyako type and 114_??_121×10⁶ years for Taro type) of the Taro mine, it can be concluded that both have almost the same genetical age or the former is somewhat older than the latter. Since this geochronological relation involves important suggestions, brief consideration on genetic problem of the ore deposits is noted.