As the COVID-19 pandemic continues, wearing a mask has become a daily routine in Korea over the last two years. This study aims to investigate the mask-wearing perception of preschoolers (ages 4–6). The questionnaire comprised 17 yes-no closed-ended questions and two open-ended questions, and interviews of the children were conducted from January to February 2022, 15 months after mandatory mask wearing. Results showed that children were aware of the need to wear a mask to protect themselves and others from the coronavirus, and they perceived it as necessary and a good thing. Most children responded that they did not feel uncomfortable wearing a mask at preschool. This perception was thought to be influenced by the caregivers’ perceptions of the mask in Korea. The way in which 4–5-year-olds perceived the mask differed from the way 6-year-olds did. Children aged between four and five seemed to perceive the mask as a physical self, while children aged six did not. As children who have experienced COVID-19 are growing up, attention is being focused on how the experience of wearing a mask affects their early childhood development.