A method of manufacturing a solid-state image sensor including preparing a wafer including a pixel region where a photoelectric conversion element is provided, a peripheral circuit region where a gate electrode of a peripheral MOS transistor for constituting a peripheral circuit is provided, and a scribe region. The method includes forming an insulating film covering the pixel region, the peripheral circuit region, and the scribe region, and forming a sidewall spacer on a side surface of the gate electrode by etching the insulating film so that portions of the insulating film remains to cover the pixel region and the scribe region, and forming a metal silicide layer in the peripheral circuit region by using, as a mask for protection from silicidation, the insulating film covering the pixel region and the scribe region.