After the Fukushima nuclear accident in 2011, there was confusion among the public caused by uncoordinated information about radiation provided by diverse channels. We explored the association between information sources regarding reconstruction progress after the disaster and mental fatigue in Fukushima. We used data from the annual public opinion survey by the Fukushima Prefectural Government on its policies from 2013 to 2015, which contained survey responses from 1,300 community residents randomly selected from the 28 municipalities in the Fukushima Prefecture. The survey contained a question assessing mental fatigue: "How often do you usually feel mentally tired or depressed?" In total, 2,130 participants (758 participants in 2013, 699 participants in 2014, and 673 participants in 2015) were analyzed. The respondents were classified as two categories, "high mental fatigue" and "low mental fatigue," based on their responses to this question. Overall, the proportion of participants with high mental fatigue was 13.2%. There was no association between the year of survey or occupation and high mental fatigue. Cluster analysis was performed to classify information sources. Then, we conducted a cross-sectional analysis of the associations between clusters of information sources and high mental fatigue. We found that unreliable information sources, such as "Internet" and "a combination of TV, radio, and word of mouth," were significantly associated with high mental fatigue, compared with reliable information sources, such as "municipal public relations in addition to major media (newspaper, TV, and radio)." These findings provide important insights into how information sources affect mental fatigue following a disaster.