Abdominal actinomycosis is a rare and chronic progressive disease, especially in children. Clinically, it has non-specific symptoms and diagnostic findings as well as low prevalence, making it very difficult to diagnose prior to intraoperative pathological confirmation. For this reason, abdominal actinomycosis is commonly misdiagnosed as appendicitis. After the histopathological diagnosis of abdominal actinomycosis is made, patients should be administered an appropriate antibiotic such as penicillin. Here we describe a case of appendiceal actinomycosis in an 18-year-old girl who was initially diagnosed with acute appendicitis.