Electronic states near the metal-insulator transition in oxide superconductors are studied in the p-d mixing model by use of the Green's-function method. Due to spin and charge fluctuations induced in the p-d hopping, electronic states near the Fermi level are strongly renormalized and show anomalous behavior in the insulator-to-metal transition; that is, the occupied p band has a tail structure at the top of the band and with hole doping, an additional narrow band develops at the Fermi level inside the charge-transfer gap, splitting from the main p band. The main p band gradually approaches the Fermi level with hole doping. The results seem to explain qualitative behaviors of experiments in photoemission and optical conductivity.