Positive-working radiation-sensitive composition

A positive-working radiation-sensitive composition comprising

• (a) a resin having an acid-decomposing group represented by the following formula (I), which is decomposed by the action of an acid to increase the solubility in an alkali developer,
• (b-1) at least one kind of compounds each generates an acid by the irradiation of an active light or radiation and contributes to the decomposition reaction of the above-described acid-decomposing group,
• (b-2) at least one kind of compounds each generates an acid by the irradiation of an active light or radiation but does not contribute to the decomposition reaction of the above-described acid-decomposing group,
• (c) a surface active agent, and
• (d) a solvent;
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• wherein, R1, represents an alkyl group having from 1 to 4 carbon atoms;
• W represents an organic group containing at least one kind of atom selected from the group consisting of an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, and a silicon atom, and at least one carbon atom, an amino group, an ammonium group, a mercapto group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted cyclic alkyl group;
• and n represents an integer of from 1 to 4.