Antigenic changes in the hemagglutinin protein of recent A(H3N2) viruses are often induced when these viruses adapt to their egg hosts. We have successfully isolated an egg-adapted influenza A(H3N2) virus, A/Saitama/103/2014, without amino acid substitutions in the antigenic sites of its hemagglutinin protein but multiple substitutions in its neuraminidase protein by serial egg passages of a cell-propagated virus. Antigenic analysis of this egg-adapted A/Saitama/103/2014 virus indicated that its antigenicity did not change from the WHO prototype cell-propagated vaccine virus, A/Hong Kong/4801/2014. Our results suggest that this strategy may facilitate egg-based vaccine production without antigenic alterations in HA by egg adaptation.