To detachably mount different optical adapters having an LED illumination section, and also, to drive the LED illumination section under optimal driving conditions.

The white LED section 10 of the optical adapter 5 has a plurality of LED elements consisting of an n serial m parallel matrix constitution D (nS and mP), and an identification resistor Rnm for identifying the kind of the white LED section 10. An operation section 7 of an endoscope section 4 is provided with an LED driving section 31 for driving the white LED section 10. The LED driving section 31 is constituted of an LED driving circuit 32 and a VR section 33.