The present invention-provides a positive resist composition wherein at least a polymer included in a base resin has a repeating unit with an acid labile group having absorption at the 248 nm wavelength light and the repeating unit is included with a ratio of 1-10% of all repeating units of polymers included in the base resin. There can be provided a positive resist composition with equal or higher sensitivity and resolution than those of conventional positive resist compositions, and in particular, by which a pattern profile on a substrate with high reflectivity is excellent and generation of a standing wave and line edge roughness are reduced.