Consumer behavior researches whose main subjects were an electronic payment and a web-based social networking service described their diffusion processes by word-of-mouth dissemination among consumers. The role of market mavens, a type of consumers who spread their capricious knowledge widely, was characteristic in this process. The agent-based simulation model based on these findings reproduced the diffusion of the research subjects. This base model was extended to a model in which multiple products compete. Fashion cycle emerged in the simulation results of the competition model in the case market mavens lead the diffusion of a product.