Poured angles of repose of spray-dried agglomerated salicylic acid and sodium salicylate particles, prepared from slurries containing these materials and gum arabic, were measured and the effect of parameters consisting of slurries inflvencing on them was determined. Concentration of sodium salicylate was the most important factor affecting on free-flowing properties of agglomerated powders as well as that of gum arabic. Angles of repose (φ_s) of the products were related to their sphericity (ψ) and their relationship was revealed by equation (1), φ=18.2ψ+33.8, where 0<ψ<0.36, Angle of repose measured by pouring and revolving cylinder method was defined as static (φ_s) and kinetic (φ_k) angle of repose, respectively, and distinction between them was clarified by a physical method. A coefficient of cohesion(C_f) indicating the cohesive property of particles was proposed, definied by equation (2), C_f=f/mg=sinθ/cosφ_ko, where φ_ko is extrapolation kinetic angle of repose, with revolution rate of cylinder being zero, and θ is the difference between φ_s and φ_ko. A calculating table of C_f was prepared, which is convenient to estimate the cohesive property of powder, based on the equation (2), and also cohesive and frictional forces of agglomerated particles were determined as 1.30×10^-5 to 1.03×10^-4 (dyne) and 1.39×10^-5 to 1.77×10^-4 (dyne), respectively. Examination of the relationshiop between these forces and sphericity showed that the larger the sphericity, the smaller were the forces.