A positive photoresist composition comprising an alkali-soluble resin, a 1,2-quinonediazide compound, an organic solvent, and a fluorinated organosilicon compound of formula (1) serving as a surfactant can be effectively coated to uniformity over large areas and is improved in resist pattern profile. Rf is a C.sub.5-C.sub.30 perfluoroalkyl group containing at least one ether bond, Q is a polyether group consisting of an ethylene glycol and/or propylene glycol polymer chain, R is H or C.sub.1-C.sub.4 alkyl, X is a divalent linking group exclusive of oxygen, Y is a divalent linking group, p is an integer of at least 3, and 0