Neuromarketing provides insights into consumers' decision-making that traditional marketing test methods cannot offer. The foundation in the process of decision-making is P300. Thus, the P300 wave is a potential Event-Related Component (ERP) used to measure consumers' decision-making process. The P300 wave represents a positive transition in human event-related potential. Therefore, the P300 is determined by measuring the amplitude and latency of the consumers. A higher P300 amplitude indicates greater confidence in the decision-making process, while a longer P300 latency indicates lower attentiveness. Thus, P300 in neuroscience, which investigates customers' responses in-depth, cannot be accomplished by typical marketing methods. For many years, P300 components such as attitudes, preferences, and information-based decision-making have been examined extensively in marketing-related research. However, a review of an ERP in neuromarketing method is fewer reported. This mini review describes some analysis on P300 and decision-making by several researchers.