  We report on the spectral evolution of 6 classical novae, V1186 Sco, V2540
Oph, V4745 Sgr, V5113 Sgr, V458 Vul, and V378 Ser, based on the low-resolution
spectra obtained at the Fujii-Bisei Observatory and the Bisei Astronomical
Observatory, Japan. In the light curves, these 6 novae show several
rebrightenings during the early phase lasting ~10 days after the first maximum
in fast novae, and ~100 days in slow novae. The early spectra of all of these
novae had emission lines with a P-Cygni profile at the maximum brightness. The
absorption component of the P-Cygni profiles then disappeared after the
maximum, and reappeared when the novae brightened to the next maximum. We
suggest that the re-appearance of the absorption component at the rebrightening
is attributable to re-expansion of the photosphere after it once shifts
sufficiently inside. From the light curves, we found that the time intervals of
the rebrightenings of these 6 novae show a similar systematic trend, which is
applicable to all types of novae: fast and slow, and Fe II type and hybrid
type. Moreover, we note the difference between the spectra at the
rebrightenings during the early phase and at the rebrightening in V2362 Cyg,
and at the oscillation during the transition phase in V1494 Aql, which means
difference of the physical mechanism of the rebrightening during the early
phase and the later oscillations.
