Lee, Jeongbok. 2016. “Unintentional Use of Discriminatory Expressions by Netizens”. The Sociolinguistic Journal of Korea 24(3). 345~377. The purpose of this study is to analyze the usages of discriminatory expressions used unintentionally by netizens on social network services (SNS), from a critical perspective, and to think about the problems and countermeasures of them. In chapter 2, we first review the previous studies related to the unintentional use of discriminatory expressions. Then we present three types of unintentional use of discriminatory expressions as ‘use discriminatory expressions in condition of changing the functions of them’, ‘use discriminatory expressions in condition of changing the target of discrimination’, ‘use discriminatory expressions in condition of not recognizing them’. In chapter 3, the unintentional usages of discriminatory expressions are analyzed upon the types of discriminatory expressions. In chapter 4, we present the problems of unintentional discriminatory expressions, and look for measures to prevent the use of them. Throughout all these discussions, we identified that netizens unintentionally use diverse expressions of discrimination on SNS, and the parties of discrimination are deeply hurt by the use of such expressions. The awareness and empathy of individual speakers are utmost important to prevent or eliminate the unintended use of discriminatory expressions. Along with them, efforts are needed urgently in fields of language education and language policy for reducing the use of these expressions and its negative impact.