Current study explores the relationship between social network service(SNS) quality factors, such as system, interface, contents, service, and emotion to trust, and intention to retain the relationship. The trust playes a role as a mediator in the causal relationship between SNS quality factors to intention to retain the relationship. To do that, study participants ages between 20s and 30s, with previous experience to SNS website usage, were examined. A total of 408 valid survey data were collected and analyzed. The results indicated that such SNS quality factors as system, service support, emotional interaction, and emotional flow showed significance on trust. Such SNS quality factors as system, service responsiveness, emotional interaction, and emotional flow showed significance on intention to retain the relationship. The responsiveness showed significance on intention to retain the relationship but not on trust. Upon reflection of the result, SNS website is primarily used for the purpose of networking and provided as a space to socialize among friends, colleagues, and other acquaintances. On such situation, the responsiveness can refer to lively opinions or active discussions among friends on the Internet space. This may be quite different from its conventional meaning, which is defined as “readiness for employees to provide service on consumers.” In addition, the responsiveness should be approached as two way relationship based on “forming and maintaining” the social network which can involve both positive and negative emotions such as jealousy, ostentation, boredom, and trust among users in the network.