This paper presents the results of room experiment on the suction effects of water-jets attached to trailing model suction head.
　The sham bed was consisted of comparatively fine sand. The experiment was carried out with two step pump delivery (0.165 and 0.283m3/min), three-step trailing speed (0.052, 0.088 and 0.129m/s) and the jet pressure was varied from 0.0 to 1.0 kg/cm2.
　In the whole case, though the increasing tendency of concentration is seen as jet pressure increases the obvious increment can't be expected.
　However, it is revealed that in the area inclosed with suction head the mixture is sucked under stable flow condition due to compulsory suspention of solids by water-jets and, hereby, the suction head can be moved smoothly.