An optical fiber in which the macro-bending loss is lowered while an MFD is maintained large, and a waveguide including the optical fiber. The optical fiber includes a core region doped with an impurity; a first cladding region formed as a layer around the core region and including holes as microstructures; and a second cladding region formed as a layer around the first cladding region and made of a homogeneous material. A relative refractive-index difference .DELTA.1 between the core region and the second cladding region is equal to or higher than 0.01% and lower than 0.3%. A total cross-sectional area of the holes in the first cladding region with respect to a total cross-sectional area of the core region, the first cladding region, and the second cladding region is equal to or smaller than 20%. A waveguide is formed using the optical fiber.