An experimental study on the improvement of aerodynamic performances of wing-body-configuration RLV (Reusable Launch Vehicle) as a space transportation system by the lateral blowing in transonic and supersonic flows has been conducted. The model configuration is a wing body which has 75° /45° double delta wing of a modified NACA0010. The lateral blowing is realized by injecting a pair of sonic jets parallel to the trailing edge of the wing. The experiments have been conducted in the wind tunnel of ISAS (Institute of Space and Astronautical Science), JAXA (Japan Aerospace Exploration Agency) under the test condition of free-stream Mach number M∞=0.9, 1.3, 2.0, Reynolds number Re=5.06×106~6.48×106, angle of attack α= 0°~30° and jet momentum coefficient Cμ=0.0042~0.0065. The results showed that the lateral blowing increases the lift and lift-to-drag ratio. From those results, we confirmed that the lateral blowing can be useful for the improvement of aerodynamic characteristics of the wing-body-configuration RLV in transonic flow as well as in subsonic region.