This study explored the effects of metacognitive processing on a creative idea generation task using the method of conceptual priming (Marsh, Bink, & Hicks, 1999). In our experiment, 81 undergraduate students were required to generate original creatures. In the task, the subjects' metacognition was manipulated through instructional variation. Factor analysis of the questionnaire data on the subjects' attitudes toward the task identified their elemental metacognitive strategies. The subjects' creative performances were examined in relation to metacognitive factors and the effects of priming. The results suggested that activating the metacognitive level of processing could cause an improvement in creativity. Implicit processes in creative thought and a search-range of the idea space were also discussed.