The question of how development of science and technology is achieved has attracted STS researchers for many years, and the importance of expectations in science and technology innovation has been indicated in the recent much STS literature. Following the global trend of the sociology of expectations, this paper focuses upon forensic technologies and discusses how expectations for forensic technologies affect their future situations.Forensic technologies, especially forensic DNA analysis, are receiving a great amount of attention and several studies have revealed that expectations and critical scrutiny of forensic DNA analysis have encourage its development. Through controversy over its credibility, DNA analysis seems to establish itself as a gold standard in forensic technologies all over the world (cf. Lynch et al. 2008); however, situations in Japan are slightly different.Based on the literature and interview research, this paper analyses how expectations and disappointment for forensic technologies varies between different countries, and describes how these differences, intertwined with various social factors, exert an influence on the diverse development process of forensic DNA analysis.