An image pickup system includes: an image sensor that performs a rolling-shutter image pickup operation; a generator; an adding section that adds image pickup signals from an image pickup signal in a predetermined frame to an image pickup signal in an Nth frame, with the predetermined frame being set as a first frame; a light source; a signal output section that outputs a signal representing either a timing of start of readout of a first line in the predetermined frame or a timing of completion of readout of a last line in a frame immediately before the predetermined frame; and a light source control section that starts light emission after an input of the signal and terminates light emission in a period after completion of readout of a first line in an N-1th frame until before a start of a first line in the Nth frame.