To solve an insight problem, a problem solver needs to relax mental constraints that prevent solving the problem, and to shift a search in an incorrect problem space into a search in a correct problem space. In this paper, we investigate how a tracking stimulus that guides problem solvers’ eye movements affects the formation and relaxation of constraints in insight problem solving. We conducted two experiments using an insight task and an eye-tracking task in which participants’ eye movements were expected to inhibit the fixation constraints in the insight task. Participants engaged in the tracking task before the constraints were formed in Experiment 1 and after the constraints were formed in Experiment 2. In Experiment 1, participants who performed the tracking task were inhibited in forming the constraints more than those in the control condition. In both Experiments 1 and 2, the tracking task affects the participants’ hypothesis formation in the insight problem solving processes. In particular, participants who were presented the tracking stimulus found a target rule faster after beginning to relax the constraints than those in the control condition.