An endoscope system (1) includes: a CMOS image pickup device (11) configured to output digital signals of a plurality of systems E/O converters (18a, 18b) configured to convert the digital signals of the plurality of systems to optical signals respectively optical fibers (21a, 21 b) configured to transmit the optical signals of the plurality of systems respectively a transmission amount changer (19) configured to convert a data amount of the digital signal of at least one system and a metal wire (22b) configured to transmit the digital signal, the data amount of which is converted by the transmission amount changer (19).
