Photoinduced changes of the piezooptical effects were discovered in the ZnO crystalline films doped by Cu. The photoexcitation was performed by the Er3+ doped 10ns glass laser at wavelength 1540nm. The piezooptical effect was determined for the diagonal tensor component at 1150nm. A nonlinear dependence of the output piezooptical response versus the photoinducing power density was established. The effect was completely reversible and disappears within the several second after the switching off of the photoinduced treatment. The possible explanation of the observed effect is given within a framework of the possible changes of Cu aggregates which is manifested through the changes of photoluminescence.