A DBR-type variable-wavelength light source having broader-band variable-wavelength characteristics and producing an output higher than that by a conventional technique even with a continuous wavelength shift of at least 6 nm. An optical waveguide formed on a substrate (21) is provided with an active-area optical waveguide (22) having a light emitting function and non-active area optical waveguides (23a, 23b) formed at the opposite ends of this active area (22), wherein each of the non-active area optical waveguides (23a, 23b) has an insulation area (25) and front-side and rear-side DBR areas(24, 29) having variable-wavelength functions, and the rear-side DBR area (29) is formed with a diffraction lattice having a length of at least 95% of the saturation value of an effective length, whereas the front-side DBR area (24)is formed with a diffraction lattice shorter than the above length and is structured to pick up an oscillation light from this front-side DBR area.