This study examined whether self-reference effect is mediated by affective process of trait adjectives based on the effect of encoding variability(Klein & Saltz, 1976). The effect of encoding variability refers to the evidence that the more variably the information about a stimulus word is encoded, the more likely that the word is retrieved in a latter free recall test. Therefore, if self-reference effect is not mediated by affective process, the task which contains both self-referece process and affective process produce greater memory performance than the tasks which contain only self-referent process or affective process. Sixteen participants engaged in four encoding tasks, each of which involved semantic, affective, self-referent, or affective self-referent process. Subsequent free recall test showed that memory performance for semantically encoded items was poorer than these for items in other three conditions. There was no difference in free recall performance between self-referenct and affective self-referent encoding conditions. These results suggest that self-referent task perse containg affective process, and this process mediates self-reference effect.