A method of graft polymerization which includes a step of forming a polymerization initiating layer in which a polymer having, on a side chain thereof, a crosslinking group and a functional group having polymerization initiating capability is immobilized on a support by a crosslinking reaction, and a step of conatacting a compound having a polymerizable functional group with the polymerization initiating layer, and then bonding the compound to the polymerization initiating layer supplying energy thereto, as well as a hydrophilic member, a printing plate precursor, a pattern forming material, a pattern forming method, a method of producing a particle-adsorbed material, and a method of producing a metal particle-dispersed thin layer film, to which the above-mentioned method of graft polymerization can be applied.