In a back-illuminated solid-state imaging device, a multilayer interconnect layer, a semiconductor substrate, a plurality of color filters, and a plurality of microlenses are provided in this order. A p-type region is formed so as to partition a lower portion of the semiconductor substrate into a plurality of regions, and an insulating member illustratively made of BSG is buried immediately above the p-type region. PD regions are isolated from each other by the p-type region and the insulating member. Moreover, a high-concentration region is formed in a lower portion of the PD region, and an upper portion is served as a low-concentration region.