  The sample of 115 B-type stars in Sco OB2 association is examined for
existence of visual companions with ADONIS near-infrared adaptive optics system
and coronograph in J and K bands. Practically all components in the separation
range 0.3"-6" (45-900 A.U.) were detected, with magnitudes down to K=16. The K
and J-K photometry of primaries and differential photometry and astrometry of
96 secondaries are presented. Ten secondaries are new physical components, as
inferred from photometric and statistical criteria, while remaining are faint
background stars. After small correction for detection incompleteness and
conversion of fluxes into masses, an unbiased distribution of the components
mass ratio q is derived. The power law f(q)\propto q^{-0.5} fits well the
observations, whereas a q^{-1.8} distribution which corresponds to random
pairing of stars is rejected. The companion star fraction is 0.20 +- 0.04 per
decade of separation, comparable to the highest measured binary fraction among
low-mass PMS stars and ~1.6 times higher than the binary fraction of low-mass
dwarfs in solar neighborhood and open clusters in the same separation range.
