Electrospinning is a technology for producing nanofibers using high voltages. In this study, we investigated jet velocities and the corresponding electrospinning mechanisms using high-speed camera observation. Moving jets were observed at various exposure times for obtaining reliable velocity data. Significant differences were observed in the velocities according to the position between the tip and collector, as a function of applied voltages. However, the jet was found to consistently progress at 3-5 m/s near the collector. This suggests that the drawing effect of the electrospun fiber, induced by bending instability, occurs in a limited region.