A band selectable amplified spontaneous emission (ASE) source of an erbium-doped fiber (EDF) which can operate in either the C- or the C+L-band region is proposed and demonstrated. The band selectable ASE source is realized using the backward feedback technique with a 1×2 optical switch in a bi-directional pumping configuration. The 25.9 mW C-band and 22.5 mW C+L-band ASE spectra are alternately obtained merely by controlling the state of the optical switch.