The present technique relates to a solid-state imaging device, a solid-state imaging device manufacturing method, and an electronic apparatus that are capable of providing a solid-state imaging device that can prevent generation of RTS noise due to miniaturization of amplifying transistors, and can achieve a smaller size and a higher degree of integration accordingly. A solid-state imaging device includes a photodiode as a photoelectric conversion unit, a transfer gate that reads out charges from the photodiode, a floating diffusion from which the charges of the photodiode are read by an operation of the transfer gate, and an amplifying transistor connected to the floating diffusion. More particularly, the amplifying transistor is of a fully-depleted type. Such an amplifying transistor includes an amplifier gate (gate electrode) extending in a direction perpendicular to convex strips formed by processing a surface layer of a semiconductor layer, for example.