  Optical and infrared light-curves of classical novae are approximately
homologous among various white dwarf (WD) masses and chemical compositions when
free-free emission from optically thin ejecta dominates the continuum flux of
novae. Such a homologous template light-curve is called a ``universal decline
law.'' The timescale of the light curve depends strongly on the WD mass but
weakly on the chemical composition, so we are able to roughly estimate the WD
mass from the light-curve fitting. We have applied the universal decline law to
the old nova GK Persei 1901 and recent novae that outbursted in 2005. The
estimated WD mass is 1.15 M_sun for GK Per, which is consistent with a central
value of the WD mass determined from the orbital velocity variations. The other
WD masses of 10 novae in 2005 are also estimated to be 1.05 M_sun (V2361 Cyg),
1.15 M_sun (V382 Nor), 1.2 M_sun (V5115 Sgr), 0.7 M_sun (V378 Ser), 0.9 M_sun
(V5116 Sgr), 1.25 M_sun (V1188 Sco), 0.7 M_sun (V1047 Cen), 0.95 M_sun (V476
Sct), 0.95 M_sun (V1663 Aql), and 1.30 M_sun (V477 Sct), within a rough
accuracy of +- 0.1 M_sun. Four (V382 Nor, V5115 Sgr, V1188 Sco, and V477 Sct)
of ten novae in the year 2005 are probably neon novae on an O-Ne-Mg WD. Each WD
mass depends weakly on the chemical composition (especially the hydrogen
content X in mass weight), i.e., the obtained WD masses increase by
+0.5(X-0.35) M_sun for the six CO novae and by +0.5(X-0.55) M_sun for the four
neon novae above. Various nova parameters are discussed in relation to its WD
mass.
