Research regarding the illusion of control was dominated by the studies examining the effect of depressive affect on the overestimation of control over uncontrollable events. However, the relative contributions of high Negative Affect (NA) and low Positive Affect (PA), as underlying dimensions of depressive states, has remained unclear. This study researched how both PA and NA had affected the illusion of control. Two weeks before illusion induction, trait PA and NA of 54 first-year university students were assessed, and just before and after illusion induction task their state forms were estimated. The induction consisted of solving unsolvable tasks and obtaining positive feedback for all the answers. The illusion of control was significantly correlated with all three PA scores, and none of the NA. After controlling for trait measures, the PA after illusion induction remained the only significant predictor of illusion. The relation of positive affect and illusory judgement in maintaining mental health were discussed.