This research was conducted in order to determine the effect of level of subjective
uncertainty on improving outgroup derogation. This study is an experimental research with post-test only two independent group design. Subjects were students of  Psychology UNS as many as 20 people, divided 11 subject in the experimental group I and nine in the experimental group II. The experimental group I was given high subjective uncertainty manipulation and the experimental group II was given low subjective uncertainty manipulation.  The treatments were a manipulation procedure level of subjective uncertainty, that modified by procedure of uncertainty in experiment by Reid and Hogg (2005). This procedure conclude manipulation of uncertainty level and identification procces into social groups. Data of outgroup derogation were collected using the IAT Format Paper by Lemm, et. Al (2008) with a validity coefficient of reproducibility is 0.904 and coefficient of scalability is 0.807 and reliability of 0.809 for Block A and 0.698 for Block B. Tests of hypothesis using Mann Whitney U-Test with a significance level of 5% yield p = 0.024. The hypothesis testing indicate p <0.05, which means Ho rejected, so that it can be concluded that subjective uncertainty level has a significant impact on improving outgroup derogation among subjects. 

Keywords: Subjective Uncertainty, Outgroup Derogation, Intergroup Behavior.