Creutzfeldt-Jakob disease (CJD) presents with rapidly progressive dementia associated with several symptoms including pyramidal, extrapyramidal, and cerebellar signs. In Japan, patients with PRNP gene mutations comprise 18.3% of CJD cases. In the present study, we report a 74-year-old man with a double mutation in the PRNP gene. He showed dysarthria, gait disturbance, and cognitive impairment. High signal intensity was observed in the bilateral cortex on brain MRI in diffusion-weighted images. There were high total Tau protein and 14-3-3 protein levels in the cerebrospinal fluid. We diagnosed him as having CJD clinically, and analyzed the PRNP gene, which revealed a V180I mutation and a M232R one, i.e., a compound heterozygous status. In our patient, the disease has very slowly progressive (total disease course, 37 months). The V180I and M232R mutations are specific mutations to Japanese CJD patients. For patients with a double PRNP gene mutation, only V180I and M232R have been known. Patients with a double mutation (V180I /M232R) in the PRNP gene might show an atypical disease course with a slow progression.