According to one embodiment of the present invention, a solid-state imaging device is provided. The solid-state imaging device includes a first-conductivity-type semiconductor region and a second-conductivity-type semiconductor region. The first-conductivity-type semiconductor region is disposed for each pixel of a captured image. The second-conductivity-type semiconductor region constitutes a photoelectric conversion element by a PN junction with the first-conductivity-type semiconductor region, and has second-conductivity-type impurity concentration that decreases from the center of the photoelectric conversion element toward a transfer gate side for transferring signal charge.