PURPOSE: An air gun is provided to maintain the certain amount of air and a certain level of pressure by including a constant pressure control unit. CONSTITUTION: An air gun having an amplification function comprises: a spray body having an inlet receiving compressed air; a valve which is arranged on the spray body and adjusts the supply of the compressed air through an operation lever; and a spray rod(106) front of the valve. The spray rod includes an amplification nozzle(115) controlling the inflow of external air.
