Tversky & Kahneman (1974) offered an explanation that in intuitive probability judgment people use judgmental heuristics which are applied easily, but which sometimes lead to errors. The present paper focused on the application processes of judgmental heuristics. It shows that from a review of previous findings it is difficult to explain preference of the judgmental heuristics in terms of cognitive parsimony (Tversky & Kahneman, 1974), and introduced a new the individuated-orientation theory (Minami, in preparation). The theory accounts for the base-rate neglect from a view-point of subjects' understanding of the task -situation, and consists with previous findings on the base-rate neglect. According to the theory, the so-called fallacies in probability judgment emerged not because of limitations to human cognitive resources, but rather because of his high ability to understand the task-situation