The results of experimental measurement and analytical estimation of the coefficient of backward reflection from targets made of various materials upon their irradiation by a picosecond laser pulse having the intensity of (0.8-4) × 10¹⁸ W/cm² are presented. It is shown that the induced surface instability leads to the formation of a profile backscattering the incident radiation. The coefficient of backward reflection achieves a few percent and has an intensity optimum depending on the target material.