After the Tohoku earthquake, people have avoided purchasing foods from Fukushima. This study examined the effect of personal attributions on purchasing while focusing on the dual-process theory. Four hundred and thirteen individuals participated in an online survey. The need for affect scale, need for cognition scale, and Cognitive Reflection Test (to objectively discriminate between affective and cognitive attribution) were administered to participants. We also assessed participants’ knowledge of radiation. The results of a multiple regression analysis showed that when need for cognition was low, there was a negative effect of need for affect on purchasing. In addition, when knowledge was sufficient, there was a positive effect of need for cognition, but negative effect of need for affect on purchasing. CRT score had no significant effect. These results suggest that avoidant purchasing is related to affective attribution, and having sufficient knowledge was not effective in reducing it.