Provided are an image sensor, an endoscope, and an endoscope system capable of achieving further miniaturization. The image sensor includes: a plurality of unit pixels 230； a plurality of first transfer lines 237 configured to individually transfer imaging signals； a constant current source 238 provided on each of the plurality of first transfer lines 237 and configured to allow the imaging signal to be output from the unit pixel 230 to the first transfer line 237； a plurality of second transfer lines 239 configured to form a capacitance in pairs with any of the plurality of first transfer lines 237 and individually transfer the imaging signal output from the first transfer line 237； a vertical scanning unit 241 and a horizontal scanning unit 244 each being configured to read the imaging signals transferred by the plurality of second transfer lines 239； and a timing generator 25 configured to cause the vertical scanning unit 241 and the horizontal scanning unit 244 to operate while allowing the unit pixel 230 to output the imaging signals.
