  In the colliders, the macroscopically large impact parameters give a
substantial contribution to the standard cross section of the $e^+ e^- \to e^+
e^- \gamma$ process. These impact parameters may be much larger than the
transverse sizes of the colliding bunches. It means that the standard cross
section of this process has to be substantially modified. In the present paper
such a beam-size effect is calculated for bremsstrahlung at Super$B$ factory
developed in Italy. We find out that this effect reduces beam losses due to
bremsstrahlung by about 40%.
