A solid-state imaging device includes a semiconductor substrate; a first conductive region of the semiconductor substrate; a first conductive region on an upper surface side of the first conductive region of the semiconductor substrate; a second conductive region below the first conductive region on the upper surface side of the first conductive region of the semiconductor substrate. The solid-state imaging device further includes a photoelectric conversion region including the first conductive region located on the upper surface side of the first conductive region of the semiconductor substrate and the second conductive region and a transfer transistor transferring charges accumulated in the photoelectric conversion region to a readout region; and a pixel including the photoelectric conversion region and the transfer transistor. The first conductive region, which is included in the photoelectric conversion region, extends to the lower side of a sidewall of a gate electrode of the transfer transistor.