Boundary Spanners (BSs) play significant roles in coordinating the relation and exchanging information and resources with other organizations. However, prior researches have not discovered the interaction among BSs in public and Nonprofit fields, especially in the context of the post-disaster reconstruction. Based on the Qualitative research with interviews from 69 BSs of Local Governments (LGs), Neighborhood Associations(NAs) and Support Groups(SGs) such as NGOs/NPOs in 18 districts of Miyagi Prefecture, the most damaged prefectures of the Great East Earthquake Japan on March 11,2011, this article explored the nature of BSs facilitated collaboration and reducing the conflict among above-mentioned organizations in 5 years reconstruction process. The initial discoveries of this research are as follows: The important characteristics and nature of the BSs are solid way of thinking, flexible reaction, experience of victims or same hometown, listening skills. The BSs in LGs faced with institutional and post-disaster limitations, but some communicated with BSs of other organizations as equal partners and utilized their discretions considering the situations on the ground. The BSs of SGs are required to have clear self-introduction, the ability to complete public projects, relations with Local governments and trust from local residents. The BSs of NAs needed to understand the activities in local community, information sharing, sound relations with respective residents, and communication with other organizations. LGs and NAs experienced the conflicts due to the slow response from LGs to the requests and questions of residents. However, BSs of SGs played translating roles between two organizations and alleviated the conflicts. The LGs and NAs suspected the intention and ability of support groups and exercised the caution not to avoid overreliance of the residents. However, the BSs of SGs have garnered the confidence from them after encouraging residents' initiatives through the respects and the realizations of the residents' opinions.