A positive type photoresist composition comprising at least one alkali-soluble resin, at least one quinone diazide compound and a compound of the general formula (I) ##STR1## wherein R.sub.1 and R.sub.2 represents alkyl groups having 1 to 8 carbon atoms or a cycloalkyl group having 1 to 8 carbon atoms, R.sub.3 represents hydrogen, an alkyl group having 1 to 4 carbon atoms or halogen, R.sub.4 represents hydrogen or a cyano group and R.sub.5 represents a cyano group or a carboxyl group.