This paper proposes a generation of polygon mesh using ray marching, which allows to create an infinite terrain in real time. The terrain is defined using an SDF model, which can precisely define the characteristics of natural terrain with little memory. And the color & depth information of the defined terrain are computed using the improved ray marching algorithm. Then the final polygon mesh is created by extracting geometric information and texture data from the GPU render target containing the color & depth values for each pixel. In addition, a multi-resolution mesh algorithm for LOD and a grid system for endless terrains are described for the extension of the ray marched mesh. Our experiments demonstrate that the proposed approach provides significant improvements over the existing terrain generation methods for computer games, flight simulators and the metaverse.