To reveal temporal relationship between Kurihashi and Ganidake granitic bodies in the Kitakami Mountains, we performed K-Ar dating for biotite and hornblende concentrates from six granitic rocks. K-Ar ages range from 130-110 Ma with one exception. There are no obvious differences between the K-Ar age of Kurihashi and that of Ganidake bodies. Also, no apparent age difference between the biotite and hornblende concentrates. Detailed petrological and mineralogical investigations are necessary for interpreting this K-Ar dating results.