[SUMMARY] This study examined the relationship between gratitude understanding and counterfactual thinking in preschool children. Participants were thirty-two Japanese children aged 4- to 6-years (16 boys, 16 girls; Mage = 67.94 months). All participants were Japanese native speakers and came from middle-income families. Each participant was tested using the understanding of gratitude task and the counterfactual task. On the gratitude task, participants were read stories that a protagonist received behaviorally or materially helping from a benefactor and asked to infer the protagonist’s emotions and reciprocity behaviors. On the counterfactual task, participants were presented with stories describing a specific causal relation and asked counterfactual questions about how the result changed if the cause was different. Results showed that 4- to 6-year-old children expressed an understanding of gratitude when a protagonist received behaviorally helping from a benefactor about his/her age. Additionally, gratitude understanding was positively related to counterfactual thinking. These results provide new evidence concerning the early emergence of children’s understanding of gratitude.