  We consider the effects of the curvaton, late-decaying scalar condensation,
to observational constraints on inflation models. From current observations of
cosmic density fluctuations, severe constraints on some class of inflation
models are obtained, in particular, on the chaotic inflation with higher-power
monomials, the natural inflation, and the new inflation. We study how the
curvaton scenario changes (and relaxes) the constraints on these models.
