ИСТИНА

The aim of the paper is to draw attention to the fact that optical flares observed in UBV bands from the famous massive X-ray binary Cyg X-1 are probably a manifestation of solar-type magnetic reconnection, which takes place in outer regions of the accretion disc-like structure surrounding the black hole or near the surface of O9.7 Iab supergiant binary component. The brightest flare observed during several hours on May 14/15, 1997, is an example of such optical flares. Observational data on and possible physical characteristics of the flare are discussed.