TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Component: The chemical reactor includes:(a) a substrate (12) where grooves (57-59) configuring the first flow path and the second flow path are formed,(b) a thermometer section for measuring temperature of the heating section,(c) a control circuit section for causing the heating section generate heat based on the temperature information of the thermometer section,(d) a third reaction section having a third flow path and causing a third reaction in the third flow path by the heat of the heating section transmitted via the second reaction section and(e) a single substrate on which three reaction sections are formed.The reaction sections are micro reactors. The heat of the heating section is transmitted from the first reaction section to the second reaction section, and further transmitted from the second reaction section to the third reaction section via the substrate. The second flow path is disposed on a periphery of the first flow path. The second and third reaction sections have vaporization reaction section (41) that vaporizes a generation fuel. It has a carbon monoxide elimination section (43) that eliminates carbon monoxide produced in the first reaction section. The first reaction section has a reforming reaction section that reforms the vaporized generation fuel. The heating section has a resistive element and a combustion section for performing heating by a combustion reaction that heats the first reaction section via the substrate. The third reaction is caused at a temperature lower than the temperature at which the first and second reactions are caused. The third flow path and the first flow path are coupled. The third flow path is disposed on a periphery of the second flow path.The distance between the first flow path and the heating section is shorter than the distance between the second flow path and the heating section. The distance between the second flow path and the heating section is shorter than the distance between the third flow path and the heating section.