Abstract: Preschooler’s understanding of relations among reality, belief, desire and emotion was investigated. Three-, 4- and 5-year-old children were required to answer the questions concerning reality-belief distinction, belief-based desire inference, and desire-based emotion inference. Results suggested that 4- and 5-year-olds were able to distinguish reality and belief correctly. It was difficult for 3-year-olds to understand the inconsistency between reality and belief. Both misreport of the reality and misreport of the belief were preschooler’s obvious errors in reality-belief distinction task, but not only “realism errors”. Most 4 and 5-year-olds were able to infer character’s desire based on belief cues. However, some 3-year-olds could not correctly infer character’s desire even if they had correctly reported character’s belief. Preschooler’s emotion understanding performance was influenced by their cognition development of belief and desire.

Key words: theory of mind, reality, belief, desire, emotion