X-ray photoelectron spectroscopy was performed to elucidate the catalytic activity of CH4 oxidation on perovskite-type Ca(Mn1-xTix)O3-delta synthesized at 1173 K in a flow of oxygen from a gel with citric acid and ethylene glycol. The Mn ion content decreases and the ratio of the Mn3+ ion in the Mn ion increases with increases in x. Ca(Mn1-xTix)O3-delta has a high catalytic activity of CH4 oxidation at x=0.4. These results indicate that the catalytic activity strongly depends on the Mn3+ ion content of the surface.