A negative-tone radiation-sensitive composition includes a polymer, a photoacid generator, and a solvent. The polymer has a polystyrene-reduced weight average molecular weight of 4000 to 200,000, and is obtained by hydrolysis and condensation of at least one hydrolyzable silane compound among compounds shown by R.sub.aSi(OR.sup.1).sub.4-a, Si(OR.sup.2).sub.4 and R.sup.3.sub.x(R.sup.4O).sub.3-xSi--(R.sup.7).sub.z--Si(OR.sup.5).sub.- 3-yR.sup.6.sub.y. "R" represents a fluorine atom, an alkylcarbonyloxy group, or a linear or branched alkyl group having 1 to 5 carbon atoms. "R.sup.1" represents a monovalent organic group. "R.sup.2" represents a monovalent organic group. "R3" and "R6" individually represent a fluorine atom, an alkylcarbonyloxy group, or a linear or branched alkyl group having 1 to 5 carbon atoms "R.sup.4" and "R.sup.5" individually represent a monovalent organic group. "R.sup.7" represents an oxygen atom, a phenylene group, or a group --(CH.sub.2).sub.m--. The content of units derived from the compound R.sub.aSi(OR.sup.1).sub.4-a is 50 to 100 mol % of the total units forming the polymer.