Resist material

A photoresist composition comprising a solution of (a) a difficulty alkali-soluble resin obtained by reacting isopropenyl alkyl ether, 2-alkoxy-1-butene, isopropenyl trimethylsilyl ether or isopropenyl benzyl ether with a resin having phenolic hydroxyl groups,

• said resin represented by the formula:
• ##STR15## wherein R.sup.11 is a hydrogen atom or a methyl group;
• R.sup.16 is a methyl group or an ethyl group;
• R.sup.12 is a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, a trimethylsilyl group or a benzyl group;
• k and l are independently a natural number (0.1<k/(k+l)<0.7);
• and the position of each substituent is the m-position or the p- position, or ##STR16## wherein R.sup.12 and R.sup.16 are as defined above;
• a, b, c and d are independently a natural number (0.1<a/(a+b)<0.7, 0.1<c/(c+d)<0.7);
• and the position of each substituent is the m-position or the p-position, (b) a photosensitive compound which generates an acid consisting of a carboxylic acid upon exposure to light, and (c) a solvent capable of dissolving the components (a) and (b), whereby the resin (a) become alkali-soluble by the acid generated by exposure to light.