A method for objectively predicting possibility of metastasis to a cervical lymph node in an early stage for an individual case diagnosed as an oral cavity cancer, and a diagnosis kit to be used in the prediction are provided. The method includes a step of assaying expression amounts of metastasis prediction genes in which the expression amounts are changed between a metastasis group and a non-metastasis group, with respect to a sample collected from a primary legion of the oral cavity cancer. Further, the method includes a step of predicting the possibility of the metastasis by comparing the expression amounts of the metastasis gene group with the expression amounts of the metastasis prediction genes in a metastasis group and/or a non-metastasis group. Herein, the metastasis prediction gene group includes two genes MSR1 (NM_138716.1) and RET (M31213.1).