An experimental study for improving the aerodynamic characteristics of wing-body configuration RLVs has been conducted. The fuselage cross-sectional configurations are isosceles right triangle and square with rounded corners. The models have single-delta wings modified NACA 0010 with 45 deg sweepback angle. The experiments were conducted in a transonic and supersonic wind tunnel at ISAS(Institute of Space and Astronautical Science), JAXA(Japan Aerospace Exploration Agency). Test conditions were as follows: Free stream mach numbers were from 0.3 to 4.0. Angles of attack were changed from -15 deg to 40 deg, but by the limitation of balance load, some cases were tested with up to 15 deg. The experimental results have shown that the model with isosceles right triangle cross-sectional configuration had good aerodynamic characteristics in the region from subsonic to supersonic, i.e. triangle model has better lift coefficient and lift-to-drag ratio than square model.