Аннотация:We consider the impact of recently detected magnetic field of O9.7 Iab supergiant component of Cyg X-1 X-ray binary system on its atmosphere. We show the magnetic pressure to be comparable with that of the stellar atmosphere matter pressure, which should lead to formation of bright spots on the surface of the star. We have used the simplest estimation of magnetic force influence on Cyg X-1 optical component atmosphere structure and brightness of the spots near magnetic poles. The upper estimation of their brightness contrast (25%) is obtained. We show that the expected spots may be observed both photometrically and spectroscopically. The possibility of magnetic field diagnostics through observation of the spots is briefly discussed.