A plasma actuator (1) includes four electrodes (11) and three dielectrics (10) and is disposed on the side of an object surface (B). When a high voltage is applied to the electrodes (11), a plasma (15) is generated at an end (10a) of each dielectric (10) exposed so as to be accessible to a gas. In the plasma actuator (1), the electrodes (11) and dielectrics (10) are alternately stacked one on another. The plasma actuator (1) includes a stepped exposed portion (X). The plasma actuator (1) in which the electrodes (11) and dielectrics (10) are arranged such that the ends (10a) of the dielectrics (10) are exposed in the normal line direction of the object surface (B) in the stacked order in the stepped exposed portion (X) can suppress the flow of the generated plasma even when the plasma actuator is exposed to a high-speed airflow under high pressure. This stabilizes the plasma.