The present invention relates to a positive photosensitive resin composition and a method for forming a pattern by using the same. The positive photosensitive resin composition includes a novolac resin (A), a polysiloxane (B), an ortho-naphthoquinone diazide sulfonic acid ester (C) and a solvent (D). The novolac resin (A) includes a xylenol-type novolac resin (A-1). The xylenol-type novolac resin (A-1) is synthesized by polycondensing an aldehyde compound with a xylenol compound.