Single crystals of the ferroelastic Pb-3(PO4)(2) were grown by the Czochralski method. We have observed the change of the domain walls by uniaxial stress applied along various crystallographic directions in the domain structure of Pb-3(PO4)(2) crystal. The crystals show the different switching results for different kinds of domain walls and different directions of applied stress. When the crystal is getting stressed above a certain value of applied stress, the wall in the (100) plane of Pb-3(PO4)(2) crystal are disappeared, and the multi-domain become a single domain. Even the stress is removed, the single domain remains in the state where a biaxial conoscope image is observed. When the single domain of the crystal is stressed along the [001] and [100] direction, this domain becomes two types of the needle-shaped domain.