The endoscope system includes an endoscope, a control unit, a beam source control unit and a type check unit. The endoscope has a radiation optical system for radiating a beam from a beam source onto a subject and an imaging optical system including an imaging device. The endoscope is removably connected to the control unit. The beam source control unit controls the emission beam intensity of the beam source according to a beam quantity specified value input from the control unit. The type check unit checks a type of the imaging device mounted on the endoscope. The beam source control unit has a plurality of control patterns representing a relationship between the beam quantity specified value and a control output value, switches to any one of the control patterns according to the check results, and controls the emission beam intensity according to the switched control pattern.