Flow on an airfoil was investigated with plasma synthetic jet actuator. Plasma synthetic jet actuator is a flow control device, which is composed of two electrodes with a.c. signal, using electrohydrodynamic (EHD) effect and induces flow around the electrodes. Plasma synthetic jet actuator has some important advantages ; for example, miniaturization is possible, mechanical maintenance is almost free. Therefore it is expected to apply for flow control around an airfoil. In this study, to observe behavior of the plasma synthetic jet actuator, experimental study was conducted. A NACA0012 airfoil, in which plasma synthetic jet actuator is embedded, was chosen, and the wake velocity behind airfoil is measured by hot wire anemometer with or without operating the actuator.