A 12-year-old girl with Gianotti-Crosti syndrome caused by hepatitis B virus (HBV) infection was admitted due to eruption on her extremities. Laboratory findings revealed elevation of transaminase, positivity for HB surface antigen (HBsAg), and an IgM type anti-HB core. The eruption and level of transaminase improved, and HBsAg became negative within 2 months of onset. Analysis of the virus revealed it to be genotype D with a genomic length of 3,182 bases and the HBsAg serotype was ayw3, which is very rare in Japan. The possible relationship between Gianotti-Crosti syndrome and HBV genotype D infection is discussed.