A radiation-sensitive resin composition comprising (A) an alkali-soluble resin having an unsaturated group, (B) a compound having at least one ethylenically unsaturated double bond, and (C) a radiation-induced radical polymerization initiator, wherein: the alkali-soluble resin having an unsaturated group (A) is obtained by reacting: 100 parts by weight of a copolymer comprising 1 to 40 wt % structural units derived from (a) a radically polymerizable compound having a carboxyl group; 1 to 50 wt % structural units having a phenolic hydroxyl group which are derived from (b-1) a radically polymerizable compound having a phenolic hydroxyl group or (b-2) a radically polymerizable compound having a functional group convertible into a phenolic hydroxyl group after the copolymerization, other structural units of said copolymer being derived from (c) another radically polymerizable compound; with 0.1 to 20 parts by weight of (d) a radically polymerizable compound having an epoxy group. The resin composition can form a radiation-sensitive film in a thickness greater than a deposit thickness and has a high resolution.