To improve fuel consumption of an internal combustion engine, and reduce discharge of air-polluting substances to the utmost by mounting a simple device on a fuel supplying line.

This combustion promoting device for the internal combustion engine is composed of a main body part 1 which is connected to the fuel supplying line of the internal combustion engine, provided with flow passage holes 3a to 3f, and provided with a cylindrical housing part 4 disposed along the flow passage holes in the longitudinal direction and along at least a part around the flow passage holes in the width direction; and a ceramic powder 7 which is filled in the housing part and for generating far infrared radiation having resonance and vibration wave length.