Provided are surface-coated inorganic particles capable of markedly reducing kneading time, and whereby a hydraulic composition having excellent fluidity can be obtained with good productivity, a method for manufacturing the surface-coated inorganic particles, a surface coating agent particularly suitable for obtaining such surface-coated inorganic particles, and a method for manufacturing a hydraulic composition. Surface-coated inorganic particles comprising at least one species of inorganic particles selected from the group consisting of hydraulic inorganic particles and pozzolanic active inorganic particles, surfaces of which are partially or completely coated by an organic dispersant, the relative surface concentration of carbon (C) being 0.35-50 and the average relative surface concentration of carbon (C) at a depth of 1-2 nm from particle surfaces being 0.15-50 when the relative surface concentration of carbon (C) with respect to silicon (Si) and calcium (Ca) in the particle surfaces is measured by XPS.
