The vortex structure generated by a single jet emit into the main flow is known as a jet in cross flow and is a fundamental phenomenon that has been reported in many studies. On the other hand, high-velocity, oscillating, sweeping jets are also attracting attention for their engineering applications, but the flow generated by sweeping jets emitted into the main flow is not fully understood due to a highly unsteady fluid phenomenon. In the present study, a large-scale vortex structure generated by a sweeping jet emitted into the main flow at an angle of 30 degrees from the wall is clarified through numerical simulation. Sweeping jets form a single stream tube near the outlet, specifically at z/d < 4.5, and gradually split into two stream tubes from z/d > 4.5. The vortex rings are generated by the interaction among the sweeping jet, the main flow, and the wall surface. The vortex rings tilt perpendicular to the main flow as they develop but dissipate due to the rotation of the high-velocity jet and transform into numerous elongated vortices.