The cognitive and neural mechanisms leading to deception were studied by the event-related brain potential (ERP) technique. In a simulated deception situation with graded monetary incentives, participants made a decision to lie or be truthful in each trial and held their response until a delayed imperative signal was presented. Spatiotemporal principal component analysis (PCA) and source analysis revealed that brain activities dominant in the left lateral frontal area approximately 800-1,000 ms post-stimulus and over the central-frontal-parietal and right frontal areas after 1,300 ms were significantly more negative in the deceptive condition than in the truthful condition. These results suggest that two serial cognitive processes, decision making and response preparation, are related to deliberate deception.