The angles of repose of nonglutinous and glutinous rice as typical biological particles were measured by the revolving cylinder test under variable ambiences ranging from air to water.The results were as follows:1) Almost the same angle of repose of glass beads resulted under the ambience in air and in water. When comparing the angle of repose of rice under ambience in water with that in air, angles of repose of 8 and 10 degrees were given for nonglutinous rice and for glutinous rice, respectively. for glutinous rice, respectively.2) As the amount of water was increased, defined as the total kg of water per 100kg of dried rice particles, the angle of repose of rice suddenly increased at 30 to kg of water. When the amount of water was 50 to 150×10-3kg, the angle of repose could not be determined because of strong cohesive force among the particles.3) Both the increase in the bulk volume and the decrease of the apparent density of rice caused by an increase of granule size since the adsorption of water had little on the measures of the angle of repose.4) A strong minus correlation existed between the apparent density and the angle of repose in water up until water was noticed on the surface of the rice granules.