We describe a case of actinomycosis of the tonsils. A 25-year-old male underwent repeated acute tonsillitis. The condition was easily recovered by oral medication of antibiotics, but soon recurred. Tonsillectomy was performed for radical treatment. The lesion was diagnosed as actinomycosis of the tonsil based on typical histopathological findings. The infection might have been weakened during oral medication of antibiotics but still persisted, and reactivated after the cessation of treatment. Tonsillectomy plays an important role in the diagnosis and removal of this condition.