Blood pressure is an important factor both in maintaining body homeostasis and in its disruption. Vascular endothelial cells (ECs) are exposed to varying degrees of blood pressure and therefore play an important role in these physiological and pathological events. However, the effect of blood pressure on EC functions remains to be elucidated. In particular, we do not know how ECs sense and respond to changes in hydrostatic pressure even though the hydrostatic pressure is known to affect the EC functions. Here, we hypothesized that the cellular responses, leading to the reported pressure effects, occur at an early stage of pressure exposure and observed the early-stage dynamics in ECs to elucidate mechanisms through which ECs sense and respond to hydrostatic pressure. We found that exposure to hydrostatic pressure causes an early actomyosin-mediated contraction of ECs without a change in cell morphology. This response could be caused by water efflux from the ECs following exposure to hydrostatic pressure. Although only a limited study, these findings do explain a part of the mechanism through which ECs sense and respond to hydrostatic pressure.