The present invention relates to a method for manufacturing a two-dimensional polymer optical waveguide, which is used for manufacturing a two-dimensional optical waveguide through simplified processes using a single imprint original master. The method includes: replicating a pattern through a first hot-embossing process on a thermoplastic polymer sheet using a single original master; forming a buffer layer on the surface of the replicated pattern; manufacturing a polymer mold having a cladding pattern on the other side without a buffer layer through a second hot-embossing process using the original master; replicating a pattern by molding the polymer mold out of an elastic material and forming an upper elastic mold and a lower elastic mold by vertically separating the elastic material; and forming middle cladding using the upper and lower elastic molds, filling regions on and below the middle cladding with core resin patterns, and performing a curing process after stacking upper and lower cladding to form a two-dimensional optical waveguide.