To identify the relationship between preschool children’s dietary diversity and parents’ care behaviours related to their diet including contents of foods and snacks, mealtime practice and parent–child communication.

Cross-sectional study. Data were extracted from the National Nutrition Survey on Preschool Children in 2015 by Japan’s Ministry of Health, Labour and Welfare.

The distribution of food diversity score (FDS) (maximum of eight points) was confirmed. The participants were divided into higher (≥4 points) and lower (≤3 points) food diversity groups. A comparison between the two groups examined parents’ socio-economic status, children’s health and living conditions, and parental care concerning children’s diets (thirteen items). A multiple regression analysis was performed relating FDS to the factors of parental socio-economic status and child health, and a logistic regression analysis was conducted to identify factors of parental care related to the higher food diversity group.

2143 persons from households with children aged 2–6 years.

Parental care concerning children’s diets was the factor most strongly associated with children’s FDS. Those factors most strongly associated with higher food diversity were nutritional balance of foods (OR: 1·76; 95 % CI 1·44, 2·16; P < 0 0001), snack contents (OR: 1·41; 95 % CI 1·07, 1·86; P = 0·014) and regular mealtimes (OR: 1·30; 95 % CI 1·08, 1·55; P = 0·005).

The findings indicate the importance of parents paying attention to the contents of children’s foods and snacks, ensuring that children eat regularly, and increasing the diversity of their diets.