To provide an inexpensive reformer for changing nature of a fluid which has a simple structure.

A base layer 2 is formed on a surface of an engine 1, and the base layer 2 is covered with the metal foil of a first layer 3 and the metal foil of a second layer 4. The base layer 2 is formed by mixing the powder of a mineral emitting negative ions in a base such as a liquid adhesive, liquid coating, or liquid synthetic resin, and applying, fusing and sticking the mixture thereof to the surface of the engine 1. In this case, the mineral is tourmaline, obsidian, serpentine, granite porphyry, ocher stone, Tenjuseki (natural stone) or the like. A powder of a substance emitting negative ions such as germanium, zirconium, vanadium, thorium, radium, radon or the like may be used instead of the powder of a mineral emitting negative ions. The base layer 2 is covered with the first layer 3 being the metal foil and the second layer 4 being the metal foil as well both of which make the effect of the base layer 2 further exerted and assume a role of protection.