We explored whether unconscious thought affects the processing of scientific technology information concerning nuclear power. Instead of conscious deliberation of cost-benefit analysis of nuclear energy, we would like to show the effects of unconscious thought on decision making. Participants were presented with all information about nuclear power and then judged the most positive as well as the most negative items. Participants in the unconscious thought condition performed a 2-back digit memory task as distractor before they made any decision regarding the nuclear power. Those in conscious thought condition were asked to carefully evaluate all presented information while participants in the immediate decision condition made a quick decision. Based on the analysis of previous studies on this topic, we attempted to obtain the potential effects of unconscious thought by modifying materials and experimental procedures including the use of noise. Even with these new manipulations, the effect of unconscious thought on decision making was not observed in Experiment 1. In contrast, we observed a significant effect of unconscious thought on decision making when task purpose was clearly presented after participants have finished reading all information regarding nuclear power. The results of the present study indicate that if the task purpose were clearly presented, the effects of unconscious thoughts on decision making could be observed.