  Oxygen abundances of 34 B-type stars in the effective temperature range of
Teff~10000-28000K with diversified rotational velocities (vesini~ 0-250km/s)
were determined from the OI triplet lines at 7771-5A, with an aim to examine
whether this OI feature can be a reliable abundance indicator for such
high-temperature stars including rapid rotators. It revealed that the required
non-LTE abundance correction is distinctly large (ranging from ~-0.6dex to
~-1.7dex) and its consideration is indispensable. On the condition that the
non-LTE effect is taken into account, this triplet is a useful O abundance
indicator (with a precision of <~0.2dex) up to Teff <~25000K, since its total
equivalent width is sufficiently large (>~200mA). In contrast, it is not
adequate for abundance derivation for stars at Teff >~25000K, where its
strength rapidly drops down toward a hardly detectable level (except for
sharp-lined stars) and its sensitivity to Teff or log g becomes considerably
large. The resulting non-LTE oxygen abundances turned out to be almost normal
(i.e., near-solar around ~8.7-8.8 within +/-~0.2dex) for most stars without any
dependence upon projected rotational velocity as well as luminosity (or mass),
which is consistent with the prediction of recent stellar evolution
calculations.
