Electric field effect on magnetism is an appealing technique for manipulating the magnetization at a low cost of energy. Here, we show that the local magnetization of the ultra-thin Co film can be switched by just applying a gate electric field without an assist of any external magnetic field or current flow. The local magnetization switching is explained by the nucleation and annihilation of the magnetic domain through the domain wall motion induced by the electric field. Our results lead to external field free and ultra-low energy spintronic applications.