Abdominal actinomycosis is a rare infection and the appendix is the most common intra-abdominal organ involved. It usually presents as an inflammatory mass, forming an abscess or fistula in the right lower quadrant. We reported a case of 22-year-old female with an actinomycosis of the appendix that was finally diagnosed by the pathologist after a routine appendectomy. The initial symptoms presented similar to acute appendicitis and the operative findings revealed local inflammatory change around the swelling appendix. For the treatment of an appendiceal actinomycosis, an en-bloc surgical resection of all involved surrounding organs and appropriate antibiotic therapy will be necessary.