The aerodynamic characteristics and the effects of winglets of a tapered supersonic biplane during the starting process have been investigated through Experimental and Computational Fluid Dynamics (EFD/CFD). Three types of the tapered biplane model were used: without winglet (type-N); with the winglet which covers only the aft-half of the wing tip (type-A); with the winglet which covers the entire wing tip (type-B). Experiment was conducted in the supersonic blow-down wind tunnel with 600mm × 600mm cross section located at the High-speed Wind Tunnel Facility of Institute of Space and Astronautical Science, JAXA. The flow conditions covered from M_∞ = 1.5 to 1.9 with increments of 0.1. Pressure-Sensitive Paint was applied to measure pressure distributions on the surface of supersonic biplane models. CFD simulations were conducted to compare with experiment and to investigate effects of the Mach numbers in detail. The tapered biplane without the winglet was found to start between M_∞ = 1.8 and 1.9. The difference of the starting Mach numbers between type-N and type-A was small. On the other hand, the starting Mach number of type-B was about 0.05 higher than that of type-N.