The present invention provides a method for correcting a shift of an output wavelength of a light source. The output wavelength shift correcting method derives simple equations through experimental processes, predicts a shift degree of the output wavelength with respect to a varied input current using the equations whenever a drive current is reset later, and adjusts a drive temperature according to the predicted shift degree, thus correcting the shift of the output wavelength. The output wavelength shift correcting method is advantageous in that it provides a method of locking an output wavelength of each light source without continuously operating a wavelength locker or a wavelength measuring device, thus reducing the operating cost of the optical communication system.