  We study the observational constraints on the exponential gravity model of
f(R)=-beta*Rs(1-e^(-R/Rs)). We use the latest observational data including
Supernova Cosmology Project (SCP) Union2 compilation, Two-Degree Field Galaxy
Redshift Survey (2dFGRS), Sloan Digital Sky Survey Data Release 7 (SDSS DR7)
and Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP7) in our analysis.
From these observations, we obtain a lower bound on the model parameter beta at
1.27 (95% CL) but no appreciable upper bound. The constraint on the present
matter density parameter is 0.245< Omega_m^0<0.311 (95% CL). We also find out
the best-fit value of model parameters on several cases.
