The purpose of this research is to identify discourse markers used in justification types in Turkish language teacher candidates' argumentative texts. Survey model was used since it was aimed to determine the categories into which support and refutation justifications are split and to identify the discourse markers which express these categories. It is a descriptive field research in which qualitative data analysis techniques were employed. The pool of the research was obtained from the texts of 3rd and 4th year students (N=100) in Turkish Language Teaching Department at Mustafa Kemal University, in 2014-2015 academic year (N=100). "Argumentative Text Writing Form" and "Justification Type Identification Form" developed by researcher used as data collection tools. Texts were by using content analysis method. Descriptive statistics (frequency (f), percentage (%)) analyses were used in the analysis of the data collected in this study. According to the results of this study; a total of 275 justifications including support justifications (f = 225) and refutation justifications (f = 50) were presented in the texts given by the students. Justification types, which are most widely used for support justifications, are reasoning (% 19.11), addition (%14.22), exemplification (%13.77) and opposition (%11.55). The least used justification types are distinction (%2.66), condition (%2.22) and sequencing (%1.77). Opposition (%34) is the most widely used justification type for refutation justifications whereas conclusion, distinction and sequencing (%2) are the least used ones. Discourse markers (n=62) were identified in 11 justification types. Examples, where these discourse markers were employed, are presented in the study through sample sentences.