Method of trimming resist pattern

A method of trimming a resist pattern, comprising:

• a step A in which a positive resist film is formed on a substrate, the positive resist film is exposed and the positive resist film is subjected to an alkali development to form a first resist pattern having an alkali-insoluble region on the surface thereof;
• a step B in which a resist trimming composition including an acid component is applied to the substrate whereon the first resist pattern is formed;
• a step C in which the first resist pattern coated with the resist trimming composition is heated and the solubility of the first resist pattern in a developing solution is changed under action of acid derived from the acid component included in the resist trimming composition;
• and
• a step D in which the first resist pattern after heating is developed with an organic solvent to remove the alkali-insoluble region of the first resist pattern, wherein the resist trimming composition comprises the acid component and a solvent which does not dissolve the first resist pattern.