A chemical amplifying type positive resist composition having excellent sensitivity and resolution, manifesting no generation of scum is provided, which comprises a resin which has a polymerization unit derived from hydroxystyrene and a polymerization unit derived from 2-ethyl-2-adamantyl (meth)acrylate, and is insoluble or poorly soluble itself in an alkali, but becomes alkali-soluble after dissociation of the above-mentioned acid unstable group by the action of an acid; a radiation sensitive acid generating agent; and polypropylene glycol.