An endoscope system includes: a phosphor and first and second blue laser light sources that emit first white light and second white light having different emission spectrums; a sensor that images an observation target under illumination with the first white light and outputs a first image signal and images the observation target under illumination with the second white light and outputs a second image signal; a movement amount calculation unit that calculates the movement amount of the observation target based on the first or second image signal; and an oxygen saturation calculation unit that calculates the oxygen saturation based on the movement amount in at least one of a first mode, in which the oxygen saturation is calculated using the first and second image signals, and a second mode, in which the oxygen saturation is calculated using the first image signal.