As the explosiveness of a chemical substance is correlated with its exothermic decomposition energy, DSC has also been used as a hazard evaluation test. Although DSC provides a safe means of performing hazard evaluation of chemicals, with the convenience of only requiring very small amounts of material, the value obtained is known to be affected by, e.g., the sample vessel material/type, the heating rate, and the sample volume. This work introduces the influences of the type and material of the sample vessel and the amount of sample on the heat behavior by providing some concrete examples. DSC evaluates both the condensed and gas phase reactions in vessels, and the factors described above have a complex effect on these reactions. Furthermore, for substances that can react with metals such as stainless steel, appropriate hazard evaluation methods have not been established. Gold plated vessels are not necessarily inert with respect to their effects on the reactions, and glass vessels have also exhibited problems. The development of pressure-resistant sample vessels made of inert substances is desirable. Careful attention should be paid to factors that could affect results to avoid deriving wrong judgments.