A method of manufacturing a solid-state image sensor includes forming a first element isolation and a first active region of a pixel area, and a second isolation and a second active region of a peripheral circuit area, forming a gate electrode film covering the first element isolation, the first active region, the second element isolation and the second active region, implanting an n-type impurity selectively into at least a part of the gate electrode film corresponding to the pixel area, and forming, after the implanting of the n-type impurity, a first gate electrode of the pixel area and a second gate electrode of the peripheral circuit area by patterning the gate electrode film. The part of the gate electrode film includes a portion located above a boundary between the first element isolation and the first active region.