Vortex shedding in the flow field causes many kinds of problems such as increase of drag and noise. Especially, the von Kármán vortex street behind bluff bodies, e.g. a tire of an airplane and a pantograph of a train, greatly contributes to them. One of the effective methods to suppress the vortices is the use of plasma actuators (PAs). A PA can induce flow by applying a high-voltage and high-frequency AC voltage to its electrodes. In the present study, we use an opposed-type PA (O-PA), which consists of two PAs facing each other. The O-PA can induce a jet in the direction perpendicular to the surface because of a collision of flows induced by the two PAs. In this study, we investigate the control effect of an O-PA on the flow around a square cylinder using an O-PA by means of the PIV measurement. First, we measure the flow induced by an O-PA. It is confirmed that the velocity of the induced flow increases as the applied voltage Vpp increases, and the O-PA induces the jet of about 1.5 m/s under Vpp = 10kV. Next, we measure the flow around a square cylinder with no control. It is confirmed that the von Kármán vortex street occurs behind a square cylinder. Finally, we measure the flow around a square cylinder under the control by the O-PA attached on the rear surface. It is confirmed that the vortex shedding behind a square cylinder is suppressed by the O-PA under Vpp = 10kV.