A purpose of the present invention is to provide a preferable separation structure of wells when a photoelectric conversion unit and a part of a peripheral circuit unit or a pixel circuit are separately formed on separate substrates and electrically connected to each other. To this end, a solid-state imaging device includes a plurality of pixels including a photoelectric conversion unit and a amplification transistor configured to amplify a signal generated by the photoelectric conversion unit; a first substrate on which a plurality of the photoelectric conversion units are disposed; and a second substrate on which a plurality of the amplification transistors are disposed. A well of a first conductivity type provided with a source region and a drain region of the amplification transistor is separated from a well, which is disposed adjacent to the well in at least one direction, of the first conductivity type provided with the source region and the drain region of the amplification transistor.