Within the non-classical theory of deformations there had been derived the formulae to divide the values of seismic waves velocities change depending upon the pressure into three components. Among them the first component is constant, equal to velocity value at the atmospheric pressure, the second and the third components change linearly and non-linearly accordingly at pressure change. Application of ratio of values of the non-linear component to the constant one allows to bring velocities dependence upon the pressure to the uniform level on different rocks. There are some ex-amples on division of velocities values of propagation of the compressional and shear waves in the rocks samples at dif-ferent pressures measured in laboratory conditions. On pla-giogranite rock on compressional waves at the pressure of 1.5 MPa the values of linear and non-linear components are accordingly equal to 2.3% and 34.5% of the complete value of the velocities. On the shear waves it makes 1.3% and 18.2% accordingly. Application of velocities division into the components allows to show more vividly the difference of character of velocities change upon the pressure, but the ratio of components allows to compare quantitatively the changes of different rocks porosity and fracturing when the pressure changes.