Currently, ethnomethodologically oriented ethnography that offer theoretical insights into how everyday practice work has been the important survey method in CHI⁄CSCW community. Ethnomethodological understandings of work and investigations of work settings has been used as a useful resource for developing new technology for the system designer of CHI⁄CSCW. The purpose of this paper is to provide an overview of traditional relationship between system designer and ethnomethodologist in CHI⁄CSCW, and is to propose a new relationship. Graham Button and Paul Dourish presented three complementary ways of integrating ethnomethodology and system design: (a) learning from the ethnomethodologist, (b) learning from the ethnomethodological accounts, (c) learning from ethnomethodology. They pointed out many problems that is relationship between designer and ethnomethodologist in their discussion. This paper's final aim is to order and to consider their problems. Then, I review the traditional cooperative work model between designer and ethnomethodologist, and discuss the development one.