An endoscope system includes: an endoscope including an image pickup device provided in an insertion portion, and configured to pick up an image of a subject to output a binary image signal; a multilevel modulation unit configured to output, through a predetermined transmission path, a multilevel signal obtained by performing multilevel modulation on the binary image signal; and a memory configured to store endoscope information on signal transmission; and a processor including a multilevel demodulation unit configured to receive the multilevel signal through the predetermined transmission path, and obtain and output the binary image signal by multilevel demodulation; and a controller configured to read the endoscope information from the memory, and determine a multilevel number in the multilevel modulation by the multilevel modulation unit based on the endoscope information read to control the multilevel modulation unit.