In this study, we developed four different scales which measure food knowledge and, using these scales, investigated the effect of acquiring knowledge through different thinking styles and across generations. In Survey 1, general consumers were surveyed, and four different scales (food-safety, food-general, additives-safety, and additives-general) were developed based on the item response theory. At the same time, the CRT (Cognitive Reflection Test: Frederic, 2005) was conducted to measure participants' thinking styles according to the dual process theory. The results showed that people with a logical thinking style scored higher than those with an intuitive thinking style on the four scales we developed. In Survey 2, we conducted surveys using the four scales with junior high school students and high school students, and compared their scores with the general consumers' data which was collected in Survey 1. The results of the four scales showed that junior high school and high school students had less food knowledge than did general consumers, but also that knowledge trends differed by types of knowledge. These results suggest that the acquisition of food knowledge among general consumers varies over time, depending on the type of knowledge measured by the scale, and, in particular, that the acquisition of knowledge of additives-safety is the slowest to develop.