$PbTiO_3$ thin films were deposited onto MgO(100) single crystal substrate by reactive D.C. magnetron sputtering of Pb metal and Ti metal in oxygen and argon gas mixture. Residual stress states and c-axis orientation ratios were studied by X-ray diffraction methods. Standard sample which did not have intrinsic stress was made by annealing method. Standard sample of $PbTiO_3$ thin films made by 700℃ 8hour annealing condition had c-axis orientation of 40 percents and c/a ratio of 1.02. Compressive stresses by intrinsic stress increased as working pressure decreased, input power increased and oxygen concentration in gas mixture increased. As the compressive stress in thin films increased, the c-axis orientation ratio increased from 60 percent to 95 percent. When strong compressive stresses existed in $PbTiO_3$ thin films, the author thought that the a-axis oriented lattice structures converted to the c-axis oriented lattice structures for consumption of compressive stresses.
As c/a ratios decreased by adding a La in the same sputtering condition, c-axis orientation ratios of $(Pb,La)TiO_3$ decreased from 95percent to 0 percent(cubic structure). It was thought that c-axis orientation ratios decreased for small c/a ratio had little consumption effect of compressive stresses.
