PURPOSE: An automatic oxygen supply system inside a manhole is provided to minimize casualties by automatically supplying oxygen the moment a manhole opens and discharging contaminated air of the manhole. CONSTITUTION: An automatic oxygen supply system inside a manhole(7) is equipped with a light sensor inside the manhole and a pressure sensor in a manhole cover stand(11). The automatic oxygen supply system supplies oxygen and discharges contaminated air of manhole by automatically operating an air supply pump with sudden changes of light and pressure the moment the manhole opens. [Reference numerals] (11) Manhole cover stand; (2) Control panel; (3) External power or storage battery; (4) Blower; (6) Air; (7) Manhole; (8) Manhole cover; (9) Pressure sensor
