The purpose of this study was to explore how children’s understanding of concealing emotion varied as a function of age, gender, and contexts. The subjects consisted of 153 children, and they were interviewed individually. The results indicated that, regarding children’s understanding of concealing demands, their understanding increased with age. They were more able to tell the concealing demands in self-protective and negative contexts. Furthermore, eight-year-old children were better at perceiving the demands of concealing emotions in prosocial contexts than six-year-olds. On the other hand, in self-protective contexts, six-year-olds were better than the four-year-old group. Besides, girls were better at perceiving the needs to conceal negative, rather than positive, emotions, whereas boys did not show such difference across emotion valences. With regard to the understanding of effective ways for concealing emotions, older children were better than the younger ones. In addition, children across age groups understood effective ways to conceal emotions more in the contexts of self-protection and negative emotions. Lastly, the degree of disguise (i.e. the intensity of facial expression of replaced emotion) was stronger when children tried to conceal negative emotions than positive ones.