The meaning of interpersonal behavior as an expression of interpersonal relation and its communicability was researched from the semiological viewpoint. Limiting the meaning level of interpersonal conducts to the degree of prescription of "aidagara (a category of relation)" of koibito (lover-sweetheart), undergraduate responded to questionaries which expored the degree of indication (markedness) of the aidagara in the Japanese society and the degree of personal connotation and inference of the markedness of 50 conducts observed between a male female. It was confirmed that necessary requiremental conducts and sufficient conditional ones of the aidagara of koibito were different and that body touching and sexal items had high degrees of markedness. Communicability (agreement between connotation by one sex and inference by the other) was generally high, but connotation of the female's vabal and male's nonvabal conducts tended to be overestimated by opposite sex. Semiological implication of the results were discussed and a need for the orientation to semanutical analysis of conducts was asserted.