Familial Mediterranean fever (FMF) is a hereditary autoinflammatory disease caused by Mediterranean FeVergene (MEFV) mutations on Chromosome 16, and characterized by periodic fever of and serositis. FMF is the result of gain-of-function mutations in pyrin that lead to interleukin-1β activation. FMF can be classified as "typical" and "atypical" types based on clinical finding and genetic screening. Although MEFV genotyping has enabled FMF to be confirmed in some cases, the diagnosis remains predominantly clinical since genotyping has shown that the disease is characterized by variable manifestations in Japanese. In 1976, the first report performed on the case of Japanese FMF with periodic fever of and serositis. Since 2002, genetic analyses are performed on Japanese FMF patients by K. Shiozaki et al. and N. Tomiyama et al. In our case, she was a 25-year-old Japanese woman with at periodic fever and abdominal pain. MEFV gene analysis demonstrated a heterozygous mutation of variant M694I, leading to a diagnosis of FMF. After the increase dose (up to 3 mg/day) of colchicine, periodic fever and abdominal pain disappeared. It is the important candidate of FMF for differential diagnosis with unexplained periodic fever and serositis, such as our case.