Flow separation is mostly an undesirable phenomenon and flow separation control is very important on airfoils. The synthetic jet is one of the effective techniques for active flow control. The synthetic jet actuator is composed of a speaker or a piezoelectric diaphragm. The purpose of this study is to develop the active stall control system of NACA0012 airfoil’s upper surface. The system detects the flow conditions (stall or unstalled) by two static pressure data alone on the airfoil. When the system detects the stall, synthetic jets automatically operate to control the stall. The maximum lift increases 16 % and the stall angle can improved at 3 ° by using synthetic jet actuator at Re = 1.5×105 based on the chord length of the airfoil. Our proposed system can enhance the aerodynamic performance of the airfoil and separation control is always attained with no stall for all flow fields produced by changing the angle of attack examined in the present study.