This article traces Ronald Dworkin's argument on the "moral reading" of constitutional law mainly from his work "Freedom's Law" (1996) and surveys some problems of his theory. These analysis shows that there are similarities between Dworkin's "moral reading" and some theories in Japan in the period of "debate on interpretation of law " (hou kaishaku ronso) in the 1950s and 1960s. But we may get a new perspective about hermeneutic approach as the methodology of constitutional interpretation through deepening the study of Dworkin's argument.