End-grain-to-end-grain welding has been the object of considerable study in the authors’ laboratory, but successful experiments have been hindered by wood defibration. End-grain butt joints obtained by friction welding with moso bamboo showed relatively good experimental results compared to beech, oak, and spruce. The average compression shear strength of the welded joints reached 5.81 MPa, and the departure of the bamboo fibers could not be observed during the welding process. A study of the microstructure of the welded surface revealed that during the welding process, hard vascular bundles within the fibers became prominent on the welded surface and acted similarly to a brush. These bundles dissipated lateral friction and protected the bamboo from cracking in the process.