  The binary of the pulsar PSRB1259$-$63 and the Be star LS 2883 has been
observed at the 2010 and 2014 periastron passages in the near-infrared (NIR)
bands using the IRSF/SIRIUS and SIRPOL. The light curves in the J-,H-, and
Ks-bands are almost identical in these periastron passages. A flare starts no
later than 10 days before periastron and the maximum brightening of about 0.1
magnitude is observed 12--17 days after periastron. The rising part of the
light curve is steeper and reaches a peak slightly earlier in the Ks-band than
in the other bands, thus a characteristic track appears on the NIR
color-magnitude diagram. The time lag between the NIR light curves indicates
that the variation in the Be circumstellar disk first occurs in an outer
region. We propose that the initial rapid contraction followed by the gradual
expansion of the disk is evoked by the rapidly changing tidal torque around
periastron and the resultant change of the optically thick area causes the
observed NIR light curves.
