In biomedical technologies that use nanoparticles, the nanoparticles are often required to translocate across a cell membrane. Application of an external electric field has been used to increase the cell membrane permeability; however, damage to the cell is of great concern. Using a molecular dynamics simulation, we show that even under a weak external electric field that is lower than the membrane breakdown intensity, a cationic nanoparticle will directly translocate across a model cell membrane without membrane disruption. We then reveal its physical mechanism. At the contact interface between the nanoparticle and the cell membrane, the electric potential across the membrane is locally enhanced by superimposing the nanoparticle surface potential on the externally applied potential, resulting in its direct translocation. Our finding implies that, by controlling the nanoparticle-induced local enhancement of the membrane potential, the cellular delivery of nanoparticles via a non-endocytic and non-disruptive pathway can be realized.