This study focuses on detailed structures of a separation bubble in controlled airfoil-flows using a DBD plasma actuator. Time-averaged surface pressure measurements and well-resolved PIV are conducted. The present PIV measurement enables the observation of the detailed flow structure near the leading edge by connecting three adjacent images of particle image velocimetry (PIV). The airfoil is NACA0015 and the Reynolds number based on the chord length is 63,000. The angle of attack is 12 deg. corresponding to the fully separated flow from the leading edge. Three types of actuation (the normal-mode case mode and burst modes with F+ = 1 and 6 ) are considered. The flow control mechanism related to a separation bubble is discussed for each case through time-averaged and phase-averaged flow fields.