The aim of this study is to develop a valid and reliable scale, which measures disloyalty in the workplace. The population of the study consisted of teachers working in the central area of Samsun in Turkey during 2017-2018 academic year. 742 teachers, who volunteered to take part in the study, constituted the sample of the study, and they were selected randomly. In data analysis process, exploratory factor analysis, confirmatory factor analysis and reliability analysis were used. According to the results of explanatory factor analysis, the scale was composed of 21 items and 2 sub-scales called manager disloyalty and colleague disloyalty and these two sub-dimensions have been explaining 0.86.7 of total variance. According to the results of explanatory factor analysis, the scale was composed of 21 items and 2 sub-scales called manager disloyalty and colleague disloyalty and these two sub-dimensions have been explaining .86.7 of total variance. According to the results of confirmatory factor analysis, all items constituted a meaningful structure under related factors and factor loadings of all items were above 0.30. As for the reliability analysis, Cronbach Alpha, Guttman and Spearman Brown analyses were carried out and Cronbach Alpha coefficient of total points of the scale was found as 0.99; the Guttman coefficient was found as 0.89 and Spearman Brown coefficient was found as 0.89. This scale of which validity and reliability analysis were completed in this study can be used by researchers studying on disloyalty in the workplace as a data collection instrument.