Mechanical constructions may obtain surface defects during a service, which can decrease their durability and robustness. This paper conducts a research of a particular case of the situation, namely, a numerical modeling of stress state of a square plate, which is exposed to biaxial stretching and the main face of which is covered by a uniform grid of spherical defects. The latter are represented here by notches, formed by cutting spherical solids from the plate. With the purpose of gaining more comprehensive study of defects' impact on the stresses, modeling is performed for configurations with different number and size of the notches. Values of the stresses are received in places and surroundings of their significant concentrations.