There is provided a sensor driving circuit that includes: an image sensor that converts light reflected from an original to be read into electric signals; a driver circuit that drives the image sensor; and a timing generator circuit that outputs timing signals for use in control of the image sensor. The driver circuit includes a first inverting buffer circuit and a second inverting buffer circuit that are equivalent to each other and arranged in series connection of two stages with the first inverting buffer circuit at the first stage of the two stages. The timing signal output from the timing generator circuit has the same polarity as the polarity of an input signal fed to the image sensor.