We report the observation of the highest velocity mode of Josephson vortex motion in mesas consisting of 5–15 intrinsic Josephson junctions with an area of 37×30 μm2 on Bi2Sr2CaCu2Oy single crystals. By applying the dc magnetic field parallel to CuO2 planes in the mesas, resonant steps and flux flow branches have been observed on the current–voltage characteristics along the c-axis of the mesas. The characteristic velocities of the intrinsic Josephson junctions are estimated to be (1.5–1.8)×106 m/s, which corresponds to the highest velocity mode, from the voltages of Fiske steps and the maximum voltages of the flux-flow branches.