To enhance the performance of an internal combustion engine by improving intake and exhaust efficiency, allowing accurate opening and closing of an intake and exhaust valve, and saving space, reducing weight, and reducing the cost of an intake and exhaust device.

Pairs of conical rotary components 1, 2 and 3, 4 are provided and rotated to function as the intake and exhaust valve. Further, an exhaust pipe 6 and an intake pipe 12 are provided having an internally tapered divergent shape for preventing surface stripping of a gas flow for quickening exchange of gas.