PROBLEM TO BE SOLVED: To provide an electronic endoscope system which can accurately measure the respective temperatures of an imaging element and tip end face by one temperature sensor.SOLUTION: The electronic endoscope system 11 includes an electronic endoscope 12, a light source device 14, a temperature sensor 30, a measurement part 41, a ROM 36, and a tip end face temperature estimation part 43. The electronic endoscope 12 includes a CMOS sensor 21 on an insertion part tip end (a tip end part 20). A light source device 14 irradiates the inside of a subject body with illumination light via a light guide 28 etc. The temperature sensor 30 outputs a signal corresponding to temperature of the CMOS sensor 21 and the measurement part 41 measures temperature of the CMOS sensor 21 based on the output signal. In the ROM 36, a calorific value of the CMOS sensor 21 and heat-characteristic data 44, including the heat resistance and heat characteristics of the tip end part 20, are preliminarily stored. The tip end face temperature estimation part 43 calculates an estimation value of temperature of the tip end face 42 from the temperature of the CMOS sensor 21 and the heat-characteristic data 44, based on a prescribed heat circuit network model about the tip end part 20.
