A number of foods, vegetables, fruits, and beverages (tea, coffee, and liqueur) contain many kinds of diterpenoids (mainly abietanes, cembranes, clerodanes, cyatanes, dolabellanes, fusicoccanes, kauranes, labdanes, pimaranes, taxanes, trachilobanes, totaranes) and their related compounds. This chapter summarizes the distribution of diterpenoids in dietary foods, vegetables, fruits, beverages, and processed foods, and their biological and pharmacological activity, effects, and application to our health, as well as metabolic pathways of several diterpenoids, which are widely distributed in dietary foods, by microorganisms and mammals.