Three-dimensional woodpile photonic crystals for 1.55 mu m telecommunication wavelength are fabricated in a GaAs wafer by the two-directional etching technique for the first time. Chlorine-based chemically assisted ion beam etching is used for deep anisotropic GaAs etching. High-precision woodpile photonic crystals with 150x150x2.25 unit cells are fabricated in a two-patterning process, which is applicable to the introduction of intentional photonic crystal disorders in epitaxially grown, active materials without wafer bonding process.