Companies are using metaphoric messages to gain attention and interest in a diversified communication environment. But there is a deep lack of the studies on the effect of metaphors in marketing. Moreover, prior studies have mixed results on the effect of metaphorical expressions. In the study, the incongruity level of metaphors is classified with congruent, moderately incongruent, and extremely incongruent levels based on schema incongruity theory to understand the effect of the metaphoric messages. The study examines to whom and which incongruity level of metaphorical messages would be effective. Furthermore, it verifies the moderation effect of personal need for structure and how it happens(cognitive and psychological mechanisms). The experiment showed that people with low personal need for structure flexibly responded to unfamiliar stimuli like metaphors because they do flexible thinking, and thus, they showed the most positive attitude to moderately incongruent metaphoric messages (inversed U-shape pattern). However, people with high personal need for structure showed the most positive attitude in the congruent message because they tend to perceive new and unfamiliar stimuli like metaphors as a task or even a stress (negative linear relationship pattern). In addition, as a result of examining mechanisms of the moderating effect, it was confirmed that for consumers with low personal need for structure, perceived novelty mediated, and for consumers with high personal need for structure, comprehensibility mediated. This study has academic significance in that it provided the framework for integrating the mixed arguments of existing studies on the effect of metaphors based on the schema incongruity theory. It provides useful managerial implications as it provides a useful guideline for determining the incongruity level of metaphoric messages.