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 (1-1) includes: a photodiode (PD) as a photoelectric conversion unit; a transfer gate (TG) that reads out charges from the photodiode (PD); a floating diffusion (FD) from which the charges of the photodiode (PD) are read by an operation of the transfer gate (TG); and an amplifying transistor (Tr3) connected to the floating diffusion (FD). More particularly, the amplifying transistor (Tr3) is of a fully-depleted type. Such an amplifying transistor includes an amplifier gate (AG) (gate electrode) extending in a direction perpendicular to convex strips (33) formed by processing a surface layer of a semiconductor layer (11), for example.