In this study, we investigated the levels of glutathione (GSH) and its oxidized form (GSSG) in more than 40 kinds of plant materials including seedling plants, grains, vegetables, and processed foods. The glutathione contents in the seedling plants were ranged from 0 to $120{mu}mol/100g$. In addition, the different levels of glutathione were observed within the same family and between species. In the case of marketed grains and vegetables, azuki and kidney beans of leguminosae contained the high levels of glutathione, whereas glutathione was scarcely detected in the processed bean foods (bean paste, soybean sauce, etc.). Overall, a higher GSH content in food may contribute to a higher added value.