In this study, a teaching material as a picture leaflet for infant was made, and the educational effectiveness of the leaflet was examined on the infants who attend one of ten nursery schools or a Kindergarten affiliated to Faculty of Education, Kochi University. The title of the picture leaflet is "A picture book on diurnal rhythm! Let's take cow milk breakfast and become a morning-typed person!" (Seikatsu-rizumunoehon, gyunyudehayanehayaoki: in Japanese). An intervention study was performed using an integrated questionnaire. The questionnaire before the intervention was administered and parents of 820 infants (711 ones attending one of the 10 nursery schools and 109 ones attending the Kindergarten) answered the questionnaire instead. All parents were asked to read the picture leaflet to their children every day during three weeks intervention period of June, 2016. Ratio of infants who had the reading of the leaflet more than 1 time for the 3 weeks was 94.5% and the average days when the reading of it was performed was 10.8 days. More than half of parents (52.4%) performed the reading it more than 10 days. Eleven percent (18 parents) of parents performed the reading every day of 21 intervention-days. In the first week of intervention, about 60% (97 infants) of the parents performed the reading in more than 4 days. Infants who had the reading it from their parents everyday got up in earlier time significantly than those who did it not in every day (U-test, z = −4.33, p < 0.01). Infants who had the reading of it every day went to bed in earlier time than the other ones who did it not in every day (U-test, z = −7.731, p < 0.001), and they slept more hours than the other ones (U-test, z = −2.30, p < 0.001). In conclusion, the reading of a picture leaflet which recommends a morning-typed life seems to be effective for How to cite this paper: Kawamata, M., Kawasumi, R., Tsuji, F., Taniwaki, N., Kawada, T., Noji, T., Krejci, M., Nakade, M., Takeuchi 1622 Psychology infants to promote the morning-typed life and quality of life (QOL) even though the intervention period is short as three weeks.