The present technology relates to a semiconductor device, a solid-state image pickup element, an imaging device, and an electronic apparatus that can suppress characteristic fluctuations caused by capacitance fluctuations due to a dummy wire, while maintaining an affixing bonding strength by the dummy wire. Two or more chips in which wires that are electrically connected are formed on bonding surfaces and the bonding surfaces opposing each other are bonded to be laminated are included and, with respect to a region where the wires are periodically and repeatedly disposed in sharing units each made up of a plurality of pixels sharing the same floating diffusion contact, a dummy wire is disposed at the center position thereof on the bonding surface at a pitch of the sharing unit. The present technology can be applied to a CMOS image sensor.