A solid-state image pickup device including a plurality of pixels, each of the plurality of pixels comprising: a photoelectric conversion portion configured to generate charges in accordance with incident light; a charge holding portion including a first-conductivity-type first semiconductor region configured to hold charges generated by the photoelectric conversion portion in a portion different from the photoelectric conversion portion; a floating diffusion region; and a transfer portion including a transfer gate electrode configured to control a potential between the first semiconductor region and the floating diffusion region, wherein a second-conductivity-type second semiconductor region is disposed under at least part of the first semiconductor region, wherein the second semiconductor region does not extend to a region adjacent to the first-conductivity-type first semiconductor region disposed under the transfer gate electrode and under the floating diffusion region wherein a second-conductivity-type impurity concentration of the second semiconductor region is higher than an impurity concentration of a region disposed at the same depth in the transfer portion and under the floating diffusion region, wherein a second-conductivity-type third semiconductor region is disposed at a deeper position than the second semiconductor region, the third semiconductor region extending under the transfer gate electrode, the floating diffusion region, and at least part of the first semiconductor region, wherein an end portion of a photoelectric conversion portion side of the third semiconductor region is away from the photoelectric conversion portion compared to an end portion on a photoelectric conversion portion side of the second semiconductor region, and wherein a first-conductivity-type semiconductor region constituting part of the photoelectric conversion portion is disposed in a region which is under at least part of the second semiconductor region and in which the third semiconductor region is not disposed. a photoelectric conversion portion configured to generate charges in accordance with incident light; a charge holding portion including a first-conductivity-type first semiconductor region configured to hold charges generated by the photoelectric conversion portion in a portion different from the photoelectric conversion portion; a floating diffusion region; and a transfer portion including a transfer gate electrode configured to control a potential between the first semiconductor region and the floating diffusion region, wherein a second-conductivity-type second semiconductor region is disposed under at least part of the first semiconductor region, wherein the second semiconductor region does not extend to a region adjacent to the first-conductivity-type first semiconductor region disposed under the transfer gate electrode and under the floating diffusion region wherein a second-conductivity-type impurity concentration of the second semiconductor region is higher than an impurity concentration of a region disposed at the same depth in the transfer portion and under the floating diffusion region, wherein a second-conductivity-type third semiconductor region is disposed at a deeper position than the second semiconductor region, the third semiconductor region extending under the transfer gate electrode, the floating diffusion region, and at least part of the first semiconductor region, wherein an end portion of a photoelectric conversion portion side of the third semiconductor region is away from the photoelectric conversion portion compared to an end portion on a photoelectric conversion portion side of the second semiconductor region, and wherein a first-conductivity-type semiconductor region constituting part of the photoelectric conversion portion is disposed in a region which is under at least part of the second semiconductor region and in which the third semiconductor region is not disposed.