This article proposed the existence of a factor which might facilitate inferential meaning in sign language. This factor would be derived from formational parameter components of signs associated with emotion. We assume that it was introduced into sign language system, and fixed as a semantic convention. In order to demonstrate such hypothesis, emotional and abstract expressions from lexical items of Japanese Sign Language were extracted, excluding iconic or socio-conventional expressions derived from conventional gestures. Thirty-six noniconic lexical items of JSL were presented, with neutral facial expressions, to 98 testee adult subjects. Using 20 semantic differential rating scales, subjects were to report impressions on the meaning of each sign item. Kinesic components of the signs were divided into 8 categories and 25 subcategories. A multivariate analysis (HAYASHI 1) was applied to these data. The results showed that some kinesic components greatly contributed to particular semantic ratings. An additional experiment with artificial body movements was executed, and similar results were obtained. These findings support the authors' predictions.