Abstract: An endoscope apparatus includes an endoscope insertion section and an optical adapter that is detachably attachable to the endoscope insertion section. In the optical adapter, an LED and a resistor for connection detection are connected in parallel to two electric contacts. In the endoscope insertion section, two signal lines are connected to electric contacts, which are connectable to the two electric contacts in the optical adapter. The endoscope apparatus includes an attachment-and-detachment determining power supply that is connected to one of the signal lines through a switching circuit, and an optical-adapter-attachment-and-detachment determining section. When connection of the optical adapter is detected, the switching circuit is switched to supply an electric current for turning on the LED from an LED turn-on power supply to the one of the signal lines.

Abstract: To provide an endoscope apparatus in which the number of signal lines inserted through an endoscope insertion section and the number of signal lines in an optical adapter are reduced to make it possible to reduce a diameter of the endoscope insertion section and reduce a size of the optical adapter. In an optical adapter 4 detachably attachable to a distal end portion of the endoscope insertion section, an LED 11 to which plural LED elements are connected in series and a resistor 12 for connection detection are connected in parallel to two electric contacts 14. To two signal lines 17a and 17b connected to electric contacts 15 connected to the two electric contacts 14, an attachment-and-detachment determining power supply 21 is connected through a switching circuit 18 and an optical-adapter-attachment-and-detachment determining section 24 is connected.