This doctoral dissertation analyzes the decision making style of the Brazilian auditor (from the point of view of the Dual Process Theory in its version modified by Regret Theory, here called TPD-m), since the decision-making pattern yield information about the way in which the auditor make judgments. Considering that auditor and accounting standard must be aligned, and considering the adoption of principle-based standards (IFRS), the objective was to deepen the studies of Jamal and Tan (2010), trying to identify whether the types of auditors identified by them (oriented by principles, by rules and by clients) could be empirically observed in the defined sample (29 partners and 35 managers of Large Six Brazilian audit firms), and whether it could find support in the literature that defines the main features of these types of auditors. The four research hypothesis were about: the lack of predominance of a single decision-making standard; the association between the patterns identified by DMI (if analytical, intuitive or emotional) and the types of auditors; homogeneity in determining what would be considered more important an audit in leasing; the existence of an association between the clusters identified by the Q Methodology and characteristics consistent with the types of auditors identified by Jamal and Tan (2010). The first hypothesis was verified with DMI Test; findings indicates that the predominant profile of auditors is analytical (explained by the accountability process experienced by professionals), which provides necessary support to affirm that the decisions taken by auditors are deliberate and carefully analyzed (if they have time available for analysis). With this result, it was not possible to verify the second hypothesis (there was no sufficient intuitive and emotional individuals to establish the desired association). The third hypothesis was verified by a lease exercise based on the Methodology Q; findings indicates no uniformity in determining what would be considered most important among the participants (in this analysis, it is clear the subdivision of analytical participants into two groups: the first focuses on the lease agreements, and the second on fair value's definition). The fourth hypothesis was verified by analyzing the most repeated words observed in the transcripts of the interviews, and the result indicates that there may be correspondence between the clusters of Q Methodology and types of auditors oriented by principles and by rules (it was not possible to conclude on the existence auditors oriented by clients). About the methods employed: the result of the lease exercise corroborates the DMI Test, as in the whole group of participants was identified analytical choosing an analytical attitudes (more literal content, more objective); Q methodology seems to be efficient in the analysis of the application of the accounting standard by the participants. About theoretical contribution: the approach of TPDm helps to explain the empirical evidence collected; furthermore, the discussion ...