<p>This paper proposes a method to simultaneously measure wave profiles and particle velocity on a wave surface by stereo imaging. About 100 markers are used as floats in the measurement. The motion of the markers is tracked by stereo cameras. From the position of the markers, the wave profile and the particle velocity on the wave surface are estimated.</p><p>Experiments were carried out in a wave tank (50m in length, 8m in width and 4.5m in depth) to validate the stereo imaging measurement method. Regular waves with the wavelength λ = 3(m) and wave height <i>H</i> = 3 ～ 20(cm) were generated in the tank and measured by the stereo imaging method. The wave height, crest height, particle velocity on the wave surface and distance between zero-crossing points estimated by the stereo imaging were compared with those measured by capacitance wave gauges or Stokes' wave theory. The comparison revealed that the errors in the 2nd-order drift velocity were less than 10% and those in other measurement items were less than 4% when the wave height is larger than 10cm.</p>