This study examines the effects of an incubation period on the creative thinking-process, particularly on the metaphor creation process. In an experiment, participants were asked to create“X like a Y” type metaphors on the basis of theme phrases, which contain adjectives and nouns. Participants in the control group were asked to create metaphors immediately after they were given the theme phrase. Participants in the incubation group were asked to generate metaphors after a distracter task. Participants in the wait group were asked to create metaphors after-thinking for three minutes. The results of the experiment revealed that when the theme phrases contained connected but complex words, the incubation group created more metaphors than the other groups. When the theme phrases contained diverse but disjointed words, the wait group created more metaphors than the other groups.