To provide a technique for increasing an intake air amount by increasing a flow rate of an intake air of the internal combustion engine and to largely improve fuel economy.

A whole intake air ionizing member 14 is rectangle, and is constituted of thin-sheet-like bag body which can be longitudinally and horizontally bent. The intake air ionizing member 14 is formed of nonwoven cloth. The intake air ionizing member 14 may be formed of fine cloth material 14a instead of the nonwoven cloth. The fine cloth material 14 constitutes the thin-sheet-like bag body as an outer surface of the intake air ionizing member 14. A first carbon fiber piece 15a which has an approximately rectangular cross section with the same width is disposed in an approximately center lateral direction in the nonwoven cloth or fine cloth material 14a constituting the intake air ionizing member 14, that is, the thin-plate-like bag body.