An electron beam welding method capable of restoring toughness even when high heat input welding is performed. The electron beam welding method comprises: forming a first weld bead (3) so as to include a groove (2) provided at the butt portions of two base materials (1), and forming a second weld bead (4) and a third weld bead (5) having a narrower width than the first weld bead (3), at predetermined positions displaced from the groove (2) and centered symmetrically about the butt portions so as to include a portion of the first weld bead (3), using a lower heat input than that used during formation of the first weld bead (3).