An optical fiber for a fiber laser has: a hollow core region; an inner cladding region having a plurality of holes that extend in a longitudinal direction of the optical fiber and surround the hollow core region; and an outer cladding region that surrounds the inner cladding region. The inner cladding region has a solid part that is made of a glass material into a part or all of which a rare earth element is doped, and the outer cladding region has a refractive index lower than that of the solid part of the inner cladding region.