The present study examined the relationship between children’s activities at a nursery school and the amount of physical activity in the COVID-19 pandemic and obtained primary data to promote future childcare activities. Healthy preschool children aged 3 - 5 (N = 21) participated in the survey. Children wore an activity tracker (Polar, A360) on the wrist of the non-dominant hand for three hours in the morning on five days, just after the state of emergency was lifted. The measurements included “activity time”, “moderate-to-vigorous physical activity (MVPA) time”, and “average heart rate (HR)”. The activity time was defined as physical activity time with an intensity of over 60% HRmax (maximum heart rate). MVPA time was defined as time doing physical activity with an intensity higher than 70% HRmax. From the results of this study, in childcare under COVID-19 pandemic, the activity time of each day was 37.8 ± 25.0 min to 87.0 ± 34.7 min, and the MVPA time was 4.7 ± 6.3 min to 33.7 ± 26.1 min, and the average heart rate was 111.3 ± 7.3 bpm at the lowest and 126.8 ± 9.9 bpm at the highest. In particular, the time of MVPA, which is expected to improve physical strength, was approximately 15min on a five-day average, which was significantly shorter than previous studies. Children’s health and development of athletic ability are hindered by insufficient opportunities for physical activities and exercise because of the current COVID-19 pandemic. Securing exercise time and increasing exercise intensity should be considered in childcare to increase children’s physical activity in childcare.