  We construct a numerical light curve model for interaction-powered supernovae
that arise from an interaction between the ejecta and the circumstellar matter
(CSM). In order to resolve the shocked region of an interaction-powered
supernova, we solve the fluid equations and radiative transfer equation
assuming the steady states in the rest frames of the reverse and forward shocks
at each time step. Then we numerically solve the radiative transfer equation
and the energy equation in the CSM with the thus obtained radiative flux from
the forward shock as a radiation source. We also compare results of our models
with observational data of two supernovae 2005kj and 2005ip classified as type
IIn and discuss the validity of our assumptions. We conclude that our model can
predict physical parameters associated with supernova ejecta and the CSM from
the observed features of the light curve as long as the CSM is sufficiently
dense. Furthermore, we found that the absorption of radiation in the CSM is an
important factor to calculate the luminosity.
