In order to estimate the frictional characteristics between six geomembranes including HDPE, EPDM etc. and geotextiles or soils, in-situ frictional tests were conducted. Developed device was very simple one and was consisted of concrete mass having a size of300 x 400 x 300 mm3 and a weight of 1.56 kN and a pulling unit with a winch. Tests were conducted at natural water content and submerged conditions. The results from in-situ tests were compared with those from laboratory tests. As the results it was found that the ratio of frictional coefficient estimated at submerged condition to that at natural water condition was about 70 – 80 % for loam ground while it was 90 % for drain sand. It was also found that the frictional coefficient between geomembrane and soil estimated at in-situ tests were about 125 to 200 % of those obtained at laboratory shear tests while the frictional coefficients between smooth surfaced geomembrane and stapled nonwoven geotextile were good coincidence between the both tests.