Provided is a wavelength tunable external cavity laser (laser beam) generating device. The wavelength tunable external cavity laser generating devices includes: an optical amplifier, a comb reflector, and an optical signal processor connected in series on a first substrate; and an external wavelength tunable reflector disposed on a second substrate adjacent to the first substrate and connected to the optical amplifier, wherein the comb reflector includes: a waveguide disposed on the first substrate; a first diffraction grating disposed at one end of the waveguide adjacent to the optical amplifier; and a second diffraction grating disposed at the other end of the waveguide adjacent to the optical signal processor, wherein the optical amplifier, the comb reflector, and the optical signal processor constitute a continuous waveguide.