This study examined the structural characteristics of the royal tomb equipped with only rail stones in the early Joseon Dynasty. Bongneung(封陵: the burial mound of royal tomb) equipped with only rail stones was constructed from 1468 to 1632. During this period, Hyeongung(玄宮: the underground chamber for the coffin of the king or queen) was constructed with lime. When the Hyeongung is completed, the soil is covered with a thickness of 1 foot parallel to the ground surface. On top of that, as the base of the Bongneung, the rail ground stone is constructed with a height of about 1.5 to 2 feet. The inside of the rail ground stone is also firmly filled with soil. On top of this, semicircular lime is installed with a convex center. Lastly the soil is divided and compacted several times to form a hill, and then covered with grass to complete the Bongneung. The notable feature is that between the Hyeongung made of lime and the Bongneung made of soil, the rail ground stone serves as a stylobate with the inside compacted by the soil.