An endoscope system includes: an image pickup device configured to output a digital signal; an EEPROM in which predetermined information concerning an endoscope is recorded; a signal control portion capable of selectively converting data of one of the digital signal outputted from the image pickup device and the predetermined information of the EEPROM to serial data and outputting the serial data; an electro-optical conversion portion configured to convert the data outputted from the signal control portion to an optical signal and output the optical signal; a universal cable; and a data switching portion switched to transfer the predetermined information from the EEPROM by the signal control portion and then transfer the digital signal by the signal control portion. The signal control portion decides through which of a metal transmitting member and an optical transmitting member the predetermined information is transmitted, based on a data amount of the predetermined information.