  The early time expansion of the space-time, namely inflation, is introduced
to solve some cosmological problems. $F(R)$ gravity is a simple extension of
the general relativity to induce the inflationary expansion. The precise
observation of the Cosmic Microwave Background gives us the information to
inspect the model of the inflation. By the Weyl transformation, $F(R)$ gravity
can be transformed to the Einstein-Hilbert term with a scalar field that plays
the role of the inflaton. In this paper we obtain general formulae to derive
the inflationary parameters including the models with a non-canonical kinetic
term. The inflationary parameters are described as functions of the inflation
potential and its derivatives. We apply the procedure to $F(R)=R+\gamma R^n$
and $R(1+\gamma R^n)^{1/n}$ models and show the allowed parameters space.
