2-Methacryloyloxyethyl phosphorylcholine (MPC) has a PC group and is one of the most well-known bioinert polymers. In this study, we evaluated the interaction between MPC and DNA, which specifically interacts with the phospholipid head group via Ca2+ ions. A MPC monolayer and poly(MPC) brush were fabricated to observe the effect of the structure on the interaction between MPC and DNA via Ca2+ ions. The poly(MPC) brush, which shows higher MPC unit density, more efficiently interacted with DNA via Ca2+ ions. Also, serum protein could interact with the poly(MPC) brush via DNA, although the brush itself hardly interacted with serum proteins. Cell adhesion was significantly provoked on poly(MPC)/DNA compared with poly(MPC) because serum protein adsorption was induced on poly(MPC)/DNA.