  Based on an analysis of the catalog of magnetic fields, we have investigated
the statistical properties of the mean magnetic fields for OB stars. We show
that the mean effective magnetic field ${\cal B}$ of a star can be used as a
statistically significant characteristic of its magnetic field. No correlation
has been found between the mean magnetic field strength ${\cal B}$ and
projected rotational velocity of OB stars, which is consistent with the
hypothesis about a fossil origin of the magnetic field. We have constructed the
magnetic field distribution function for B stars, $F({\cal B})$, that has a
power-law dependence on ${\cal B}$ with an exponent of $\approx -1.82$. We have
found a sharp decrease in the function $F({\cal B})$F for ${\cal B}\lem 400 G$
that may be related to rapid dissipation of weak stellar surface magnetic
fields.
