Dynamic stall is characterized by the formation and advection of a dynamic stall vortex. This process causes a rapid increase in lift followed by a sudden lift decrease. As a result, highly unsteady aerodynamic loads are generated, causing a negative effect on aerodynamic performance and stability. In this study, Large-Eddy Simulations were conducted to investigate dynamic stall control using a plasma actuator with a feedback control strategy. Dynamic stall was simulated for the NACA0012 airfoil-flow with a ramp-type pitching motion, in which the angle of attack was increased from 8° to 30°. Simulations were performed at Reynolds numbers of 2.56×10⁵ and 6.4×10⁴. A pressure sensor was installed on the airfoil surface, and its location was varied from 0% to 20% chord in 5% increments. This study focuses on the contraction and collapse of laminar separation bubbles. A feedback control law was developed based on the variance of the pressure coefficient. An increase in the variance was interpreted as the contraction of the laminar separation bubble, triggering activation of the plasma actuator. In contrast, a decrease in the variance indicated advection of the dynamic stall vortex, leading to deactivation of the actuator. At a Reynolds number of 2.56×10⁵, the proposed control law delayed the formation of the dynamic stall vortex by approximately 4° compared with the no-actuation case, resulting in the delayed stall onset. Furthermore, the actuator activation time was reduced compared with a predetermined control scheme. Similar trends were observed at a Reynolds number of 6.4×10⁴, where the advection of the dynamic stall vortex was delayed by approximately 3°, accompanied by the delayed stall onset of stall and a reduced actuator activation time. These results demonstrate that the proposed feedback control law effectively delays dynamic stall under different Reynolds number conditions.