Primary leptomeningeal lymphoma is a rare disorder, and the neuroradiological characteristics or the complication of this rare disorder have not been well reported. We reported herein a patient with a primary leptomeningeal lymphoma who has complication with subdural hematoma. The patient complained of headache and vomiting. Neurological examination revealed progressive cranial nerve palsy. Cerebrospinal fluid examination disclosed monoclonal proliferation of atypical B-lymphocytes. Cranial computed tomographic scans showed a left frontal mass with convex form to the brain parenchyma. T1-weighted magnetic resonance (MR) images disclosed subacute subdural hematoma. However, proton-weighted MR images showed high signal intensity in subarachnoid space, which suggested leptomeningeal lymphoma. He underwent craniotomy, and the diagnosis of leptomeningeal lymphoma complicated with subdural hematoma was confirmed. Systemic examinations disclosed no lymphomatous lesions except for leptomeningus, and the diagnosis of primary leptomeningeal lymphoma was established. We suggested that subdural hematoma was associated with primary leptomeningeal lymphoma in this patient. Cerebrospinal fluid examination and proton-weighted MR imaging should be performed when progressive neurological abnormalities are found in patients with subdural hematoma.