In Japan, a decrease in young children's physical activity became a social problem. But young children's physical activity plays an important role to develop. Therefore, it is important how young children's physical activity be done in the child care. So, Child care worker's idea concerning young children's physical activity was examined in the present study. The questionnaire survey was done for 226 child care workers. It has been understood that the child care worker thinks young children's physical activity to be important from the relation between the life rhythm and physical ability from the result of the present study. In addition, it has been understood that the child care worker is executing young children's physical activity in consideration of the young children's development and the concern. However, young children's physical activity relied on child care worker's sense and was done in the child care. As the cause, the accumulation of the research of young children's physical activity is a little, and there is no index to which the child care worker refers. It will be necessary to accumulate a more detailed research of young children's physical activity in the future. Especially, it is necessary because the child care worker needs the research of the children's physical activities relation to life rhythm, to physical ability.