The frequency doubling process in crystal has been reconsidered based on the theory of partial coherence in the manuscript the coherence theory concerning the frequency doubling:Ⅰ. definition and description, and the theoretical description of distribution of radiant intensity of the second harmonic wave excited by the incident fundamental wave is finally expressed afresh by the theory of partial coherence. But we may ask whether we might not prove the validity of the result obtained from such abstract idea supplemented by the requirement of demonstrating feasibility of the theory of partial coherence. The author will inquire into the consistency in this contribution between the line of reasoning in the above paper with the former description of the Franken and Ward, and furthermore we see whether the definition and the demonstration based on it are tenable or not.