The present invention relates to a positive resist composition and to a pattern forming process using the same. The present invention provides: a positive resist composition having an enhanced etching resistance and an excellent resolution and being capable of providing an excellent pattern profile even at a substrate-side boundary face of resist, in photolithography for fine processing, and particularly in lithography adopting, as an exposure source, KrF laser, extreme ultraviolet rays, electron beam, X-rays, or the like; and a pattern forming process utilizing the positive resist composition.