The purpose of this study was to explore the influence of varied types of other-presence on experimentally induced anxiety responses. Thirty-six female subjects were randomly assigned into the four experimental groups varied in two conditions of their relationships. These groups were named, respectively, Friend/Co-Active (FC), Friend/Audience (FA), Stranger/Co-Active (SC), and Stranger/Audience (SA). Subjects in Co-Active condition were connected in a series circuit and would receive an electrical shock in together. After the collection of subjective ratings for affiliation, anticipatory arousal was measured directly by physiological and subjective indices while waiting for the onset of electrical shock during one minute. The results were as follows; (1) In arousal level, SA was the highest, and FC was the lowest of the four experimental groups. (2) The Stranger conditions (SC, SA) were higher than the Friend conditions (FC, FA) in both physiological and subjective indices of anxiety responses. (3) The arousal level of SC was almost the same as that of FA. This implied that the Co-Active condition might heighten the intimacy of mutual relationship even if they were strangers to each other.