A new genus of Prionoceridae, Idgiaites gen. nov. (type species: I. jurassicus sp. nov.), is described and illustrated from a well-preserved impression fossil from the Middle Jurassic Jiulongshan Formation collected at Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia, China. This is the first representative of Prionoceridae described from the Mesozoic era, and the presence of this family in the Jurassic indicates that cleroids were quite diverse during the early evolution of polyphagan beetles. The occurrence of plants in the same Formation may indicate that Idgiaites like it's modern confamilials were pollen-feeding.