An endoscopic gaseous material feed system comprises a gas feeder 3 having a gas tank 60 containing carbon dioxide gas, a light source 2 incorporating an air pump 23 for air supply, an endoscope 1 internally having a gaseous material passage for a gas or air supply to a body cavity of a patient or examinee, and a controller 80 adapted to put the air pump 23 of the light source 2 in a deactivated state upon detection of a start of a carbon dioxide gas supply from the gas feeder 3.