The present technology relates to an image sensor capable of suppressing the power consumption, and an electronic device. A reference signal output unit configured to output a reference signal of which a level is changed, includes a plurality of DACs including a plurality of current sources, and a plurality of switches controlling a current flowing from the current source, and a load resistance for outputting the reference signal. Further, the reference signal output unit is connected to three or more power sources, and in combinations of two power sources in the three or more power sources, each of two or more types of combinations of the power sources includes a first path through which the current controlled by the switch, flows, and a second path through which a current in the same direction, flows to the load resistance. The present technology, for example, can be applied to an image sensor or the like, performing reference signal comparison type AD conversion.