This paper aims to clarify the role of sign interpreters as an interactional participant in the multi-lingual and multi-party field that consists of Hearing people, Deaf people and sign interpreters. Previous translation studies pointed out role of sign interpreters from the perspective of discourse analysis. However they had not discussed about the role of interpreters from the view point of multi-party interaction. Therefore, we anal- ysed the procedures of getting addressees for turn-opening based on turn-taking system (Sacks et al. 1974). As a result of analysis, the problems concerning with the property of field were solved by sign interpreters who acted as interconnecting point of verbal and signed sequences. That is, sign interpreters played a traffic controller of interaction.