Human behavior is known to be heterogeneous and fluctuates temporally. Many studies have focused on the fluctuation of Inter-Event Times (IETs), the times between one action and the next in various types of human behavior. The existence of this fluctuation cannot be explained by a stationary random Poisson process and is called burstiness. In this study, we collected human physical activity data while specifying the age of the subjects and their situations (e.g., children's play and adults' housework) and analyzed their event time series. We confirmed that burstiness both in children and adults. Especially, burstiness in the physical activity of 2-3 year children is, for the first time as far as we know, observed. We also confirmed that each activity situation has its own specific IETs distribution characteristics. Our results may provide important clues to identifying the mechanisms of burstiness in human physical activities.