Growing evidence has suggested interesting dissociations between conscious and sub- conscious processing in insight problem solving. It indicates a possibility that the process of insight problem solving is largely governed by an implicit learning mecha- nism that detects the differences between current and goal states, and regulates the strengths of the responsible operators. If the implicit learning mechanism takes part in the insight problem solving process, the process might be affected by a hint stimu- lus subliminally presented, because such a stimulus could not be used by the explicit learning system. We examined this possibility using the continuos flash suppression technique. The results of two experiments showed that subjects subliminally presented with the goal state of a difficult insight puzzle solved it much faster than those in the control group. These results were discussed in terms of unconscious nature of insight problem solving, gradual tuning of operator strengths during the impasse, and roles of subliminal hint information in the problem solving processes.