  The 2000 outburst of V445 Puppis shows unique properties, such as absence of
hydrogen, enrichment of helium and carbon, slow development of the light curve
with a small amplitude that does not resemble any classical novae. This object
has been suggested to be the first example of helium novae. We calculate
theoretical light curves of helium novae and reproduce the observational light
curve of V445 Pup. Modeling indicates a very massive white dwarf (WD), more
massive than 1.3 Msun. The companion star is possibly either a helium star or a
helium-rich main-sequence star. We estimate the ignition mass as several times
10^{-5} Msun, the corresponding helium accretion rate as several times 10^{-7}
Msun yr^{-1}, and the recurrence period as several tens of years. These values
suggest that the WD is growing in mass and ends up either a Type Ia supernova
or an accretion induced collapse to a neutron star.
