A method for preparing a printing plate material containing a substrate having thereon a hydrophilic layer, comprising the steps of (i) applying on the substrate an aqueous coating solution for the hydrophilic layer, the coating solution containing colloid of spherical metal oxide particles and having a pH value of 8 to 12 to obtain a coating layer; and (ii) heating the printing plate material so that a surface temperature of the coated layer is raised to 130 to 300.degree. C., so as to dry the coated layer.