  Light curve analysis of decay phase of nova outburst are summarized. Nova
duration is determined by the strong wind mass-loss which depends only on the
white dwarf mass. Fast novae correspond very massive white dwarfs and very slow
novae correspond almost lower mass limit of white dwarfs. This relation is
shown in both of classical novae and recurrent novae. Light curves are
theoretically reproduced for recurrent novae, U Sco, V394 CrA, CI Aql, V2487
Oph, RS Oph, T CrB, V745 Sco and V3890 Sgr, using binary model composed of a
white dwarf, an irradiated accretion disk, and partly irradiated companion
which is shadowed by the accretion disk. From the light curve fitting, we
conclude that most of these objects contain a very massive white dwarf close to
the Chandrasekhar mass limit (1.37 M_\sun for U Sco, V394 CrA T CrB and RS Oph,
1.35 M_\sun for V2487 Oph, V3890 Sgr and V745 Sco). They are strong candidates
of type Ia SN progenitors. Population II novae have trends of slow evolution
and small expanding velocity compared with disk novae.
