Use of insecticides can have disruptive effects on the environment. Replacing the chemical compounds in these insecticides with plant materials, however, can be a safe method with low environmental risk. In the current study, chemical composition and insecticidal activities of the essential oil from cardamom, Elettaria cardamomum L. (Maton) (Zingiberales: Zingiberaceae) on the adults of three stored product pests was investigated. Results indicated that essential oil of E. cardamomum toxic to the bruchid beetle, Callosobruchus maculatus Fabricius (Coleoptera: Bruchidae), the red flour beetle, Tribolium castaneum Herbst (Coleoptera: Tenebrionidae), and the flour moth, Ephestia kuehniella Zeller (Lepidoptera: Pyralidae). Adults of E. kuehniella were more sensitive than the Coleoptera. Also, the highest mortality of these insects was seen after 12 hours. Results of the LT50 tests showed that the lethal time of mortality occurred between 10–20 hours in various test concentrations. Essential oil of E. cardamomum had a good efficacy on oviposition deterrence of C. maculatus females, too. The chemical constituents of the essential oils were analyzed by gas chromatography—mass spectrometry. The major constituents of cardamom were identified as 1,8-cineol, α-terpinyl acetate, terpinene and fenchyl alcohol. These results suggest that essential oil of E. cardamomum is a good choice for control of stored product pests.