An inflatable decelerator is promising as atmospheric entry systems in the next generation. Although the various kinds of inflatable decelerators were proposed and researched in the past, we focus especially on a flare-type membrane aeroshell sustained by an inflatable torus. The flare-type membrane aeroshell may easily make re-entry systems simple and light-weighted because the aeroshell can be composed mainly of light-weighted membrane. As an important milestone of the development of the vehicle, a re-entry flight demonstration of the vehicle with the flare-type membrane aeroshell was carried out using Japanese S-310 sounding rocket in August, 2012. This flight experiment was successfully accomplished and various data, including the attitude of the vehicle during the supersonic atmospheric re-entry, was acquired. The attitude dynamics was qualitatively reconstructed base on the flight data, which shows that the vehicle entered into the atmosphere with high angle of attack and experienced a drastic attitude motion caused by the aerodynamic force. After the initial significant motion phase, the attitude behavior of the vehicle calmed down before the successive deceleration phase. That is, the vehicle made a flight with a normal attitude and, as planned, its attitude was almost stable after the atmospheric-entry. In all, it was confirmed that the attitude stability of vehicles with a flare-type membrane aeroshell could be realized on a supersonic atmospheric-entry.