A method for manufacturing a solid-state image pickup device is provided. A first pixel isolation member is formed in a semiconductor substrate including pixels by implanting impurity ions in a first region of the substrate to separate pixels in the first region from each other when viewed from a surface of the substrate. A second pixel isolation member is also formed in the substrate by forming a trench in a second region of the substrate different from the first region to separate pixels in the second region from each other, and filling the trench with an electroconductive material harder to polish by CMP than the substrate. The thickness of the substrate is reduced by CMP on a rear surface of the substrate using the second pixel isolation member as a stopper.