  We propose a possible measurement of the time variability of the vacuum
energy using strong gravitational lensing events. As an example we take an
Einstein cross lens HST 14176+5226 and demonstrate that the measurement of the
velocity dispersion with the accuracy of $\pm$ 5 km/sec will have a chance to
determine the time dependence of the vacuum energy as well as the density
parameter with the accuracy of order 0.1 if one fixes the lens model.
