To provide a fuel activator improving fuel consumption rate and causing purification of exhaust gas and reduction of noise, especially in a diesel engine.

A tape 16, on which the fuel activator containing powder acquired from a surface of a compound radioactive material in which powder of radium ore is fused on a surface of uranium ore as a component, is adhered, is wound around a fuel hose 10. Fuel transported to the engine 14 from the fuel tank 12 reaches an engine 14, in state where molecule groups are atomized by the fuel activator and are efficiently burned.