  The effect of pre-inflation physics on the power spectrum of scalar
perturbations is estimated and there is a possibility that the pre-inflation
physics explains the Wilkinson Microwave Anisotropy Probe data if the length of
inflation is near 60 e-folds. Considering various pre-inflation models with
radiation-dominated or matter-dominated periods before inflation, the power
spectrum of curvature perturbations for large scales is calculated, and the
spectral index and running spectral index are derived.
