The present invention provides a positive photosensitive resin composition which can be developed with a tetramethylammonium hydroxide aqueous solution with a usual concentration, has high sensitivity and excellent resolution, and is excellent in heat resistance, planarization properties, transparency, low water absorption or the like. Further, the present invention provides a method for arbitrarily forming a pattern having a semicircular or trapezoidal section by using the composition. The positive photosensitive resin composition of the present invention comprises an alkali-soluble resin, a 1,2-quinone diazide compound, a crosslinking compound having at least two epoxy groups and a surfactant, and the alkali-soluble resin is a copolymer comprising a carboxylic group-containing acrylic monomer, a hydroxyl group-containing acrylic monomer and an N-substituted maleimide as essential components. By changing the postbake conditions, the composition can arbitrarily form a pattern having a semicircular or trapezoidal section.