We report a patient with non-Hodgkin's lymphoma who developed a unilateral left oculomotor nerve palsy. Only eyelid lifting and vertical gaze were involved. Lateral gaze or sizes and light reactions of pupils were not involved. Magnetic resonance imaging revealed an enhancement of an upper part of left cavernous sinus and the posterior clinoid process. It was conceivable that lymphoma invaded the upper branch of oculomotor nerve. Such neurological symptoms in cases of oculomotor nerve palsy by lymphoma have not been reported previously. Because cranial neuropathy could occur as the first sign of lymphoma, lymphoma is an important differential diagnosis for the partial oculomotor palsy such as our present case.