Abstract: A high-speed transportation mechanism on rail track, wherein sleepers 4 are laid out on gravel 5 on the ground. A first rail (mono rail) 3 for supporting the weight of a vehicle 1 is laid down on the sleepers 4. A second rail (guide rail) 7 is suspended from an upside-down L sectional shape column 8 at an upper position opposed to the lower position of the first rail 3, the vehicle 1 will not fall on its side because a wheel of a lower side carriage 2, is fitted closely to the first rail 3, and a wheel of an upper carriage 6 is fitted closely to the second rail 7. A plurality of vehicles 1 are connected to each other through couplers 9, whereby the vehicle 1 can be run safely and stably at high speeds on a centrifugally forced curved line because it can run at any inclination angle. Thus, risks such as yawing, rising, and derailing of the vehicle 1 can be reduced.