A photosensitive resin composition for an organic layer pattern includes about 100 parts by weight of an acryl-based copolymer and about 5 to about 100 parts by weight of a 1,2-quinonediazide compound. The acryl-based copolymer is prepared by copolymerizing about 5 to about 60 percent by weight of an isobonyl carboxylate-based compound based on a total weight of the acryl-based copolymer, about 10 to about 30 percent by weight of an unsaturated compound carrying an epoxy group, about 20 to about 40 percent by weight of an olefin-based unsaturated compound, and about 10 to about 40 percent by weight of one selected from unsaturated carboxylic acid, unsaturated carboxylic acid anhydride, and a mixture thereof. Methods of manufacturing a TFT substrate and a common electrode substrate using the photosensitive resin composition are also provided. Advantageously, the organic layer pattern may have a mountain structure having an improved local flatness without concave and convex structures.