A 14-year-old male cocker spaniel was diagnosed with sebaceous gland adenoma in the right external ear canal. Macroscopically, a whitish nodular mass, 3.1 x 3.5 x 2.2 cm in size, moderate to firm in consistency, was seen. The cut surface of the tumoral mass was solid. In the microscopical examination, the tumoral mass was formed by many lobules composed of 2 types of different cells (basaloid and sebaceous cells). Because of the mass within the external ear canal, the dog had severe otitis externa and problems in hearing.