The explosion at the Fukushima Nuclear Plant highlighted serious social concerns about risk communications; the public found it difficult to take preventive actions based on scientific information of radioactive fallout. We investigated public perception of the risks from low dose radiation and the role of information providers through the Internet survey focusing on parents in four Japanese regional groups. Mothers felt more anxious than fathers in Fukushima but not in further groups, and that the furthest group felt the most ambiguous anxiety. Their anxiety derived from distrust of the government and uncertainty about scientific information, rather than the lack of knowledge although risk communication emphasized learning the scientific mechanism. The mediators should provide more information for individual decision-making of day-to-day risk management in regions with different levels of radiological contamination; key issues include improving parents’ perceived control to their lives and easing their tension of responsibility to children’s health.