This study examines the influences of space design of the nursery room to "early infants's behavior and nursery workers thought" by action research method. Space design of the nursery room was modified two times within a year by nursery workers and we observed the changes which occured in the 0-year class's children's behavior. As a result we found two facts. One, children became more steady, concentrated, and continued according to modification of space design of the nursery room. Second, nursery workers came to recognize the influence of the environment's power. We came to the conclusion that quality of nursery room environment is important to "quality of nursery".