Background: During and after the Fukushima nuclear disaster (FND), many parents were concerned about the effects of radiation on the health of their children. Purpose: To clarify the factors that influenced general workers living with children and the effect of child age groups in implementing preventive behaviorsagainst radiation following the FND. Materials and Methods: A descriptive study of preventive behaviors among general workers was carried out 3-5 months after the nuclear disaster. The subjects were 1,394 regular workers, who took part in radiation seminars run by the Fukushima Occupational Health Promotion Center between July and September, 2011. In total, 1,217 responses were submitted, of which 1,110 were eligible for the present study. This anonymous questionnaire survey inquired about the presence and age of children in the household and about radiation preventive behavior implemented after the FND. The contribution of each variable was assessed by logistic regression analysis. Results: General workers in Fukushima who lived with younger children performed more preventive behavior against radiation during and after the FND. In particular, both location-related and daily routines were practiced significantly more frequently (p<0.01) by workers living with a child in the age ranges of 0-6 (8 of 10 items) and 7-12 (5 of 10 items). Conclusions: This is the first study to assess the positive association between living with children by age group and increased preventive behavior against radiation implemented by general workers after the FND.