Here we report the molecular evolution of the VP1 and RdRp genes in HuNoV GII.2. Our main findings and hypothesis are as follows. (1) Four genotypes of GII.2 (GII.P2-GII.2, GII.P16-GII.2, GII.P12-GII.2, and GII.Pe-GII.2) were detected in Japan in 2004–2015. (2) A common ancestor of the current GII.2 virus strains circulated around 1956. (3) VP1 gene evolution seems to depend on the RdRp gene. The VP1 gene in a prevalent HuNoV genotype GII.2 might evolve uniquely by transfer of the RdRp gene.