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. In this review, our recent molecular dynamics simulation study of the nanoparticle translocation across cell membrane under external electric field is presented. Firstly, a finding, where a cationic nanoparticle directly translocates across a model cell membrane without membrane disruption even under a weak external electric field that is lower than the membrane breakdown intensity, is presented. The physical mechanism of this nanoparticle translocation is then explained in terms of the interfacial electric potential between the nanoparticle and the cell membrane. Our finding can provide an insight into the cellular delivery of nanoparticles via a non-endocytic and non-disruptive pathway.