An insufflation system configured to supply a predetermined gas into a body cavity of a subject includes: an automatic air supply conduit line configured to automatically supply a gas into the body cavity to maintain a predetermined pressure in the body cavity a manual air supply conduit line configured to supply a gas into the body cavity by a manual operation a function selection button provided in an endoscope and a control unit configured to cause, in accordance with an operation of the function selection button, an air supply conduit line selected by an operation of the function selection button to be in a communication state, and cause a non-selected air supply conduit line to be in a disconnection state.
