Chromatic aberration of the light‐focusing plastic rod (LFR) prepared by the two‐step copolymerization technique of aM1‐M2monomer pair is discussed theoretically. It is found that the chromatic aberration depends on the respective optical properties of theM1polymer andM2polymer alone, and that the selection of aM1‐M2monomer pair is the most important determinant for low chromatic aberration. The requisites for low chromatic aberration are shown. Furthermore, we prepared a LFR with low chromatic aberration by using diethylene glycol bis (allyl carbonate) asM1and 1,1,3‐trihydroperfluoropropyl methacrylate or 1,1,5‐trihydroperfluoropentyl methacrylate asM2; the chromatic aberration parameter is in good agreement with the theoretical value.