A 61-year-old alcoholic man was admitted to our hospital because of disturbance of consciousness. He also exhibited external ophthalmoplegia, diplopia and mild rigidity, but tendon reflex was normal. On brain MRI, diffusion weighted images (DWI) and apparent diffusion coefficient (ADC) map depicted high intensity in the splenium of the corpus callosum. DWI showed high intensity, but ADC map depicted iso-intensity in bilateral precentral gyri. Marchiafava-Bignami disease (MBD) was diagnosed. After intravenous drip of vitamin, his symptoms improved rapidly and the abnormal MRI findings in the splenium of the corpus callosum and bilateral precentral gyri disappeared gradually. MBD is pathologically characterized by demyelination and necrosis in the corpus callosum, which are generally caused by cytotoxic edema. Our case suggests that vasogenic edema may occur at the early stage of the MBD.