Gnomon (圭表, Gyupyo) is an observational instrument to figure out the length of a year as well as the 24 seasonal divisions of a year by measuring the shadow stick when southing. China has a long history of gnomon and a few ancient gnomons are remained now. In Korean history, Gnomon appeared first in the Sejong-Sillok (世宗實錄) and was installed inside the royal palace of Joseon dynasty, Gyeongbok palace (景福宮). Generally Gyu (圭) made of stone is placed on the bottom horizontally, and the Pyo (表) made of bronze is stood vertically on it. The first gnomon manufactured during King Sejong's period (世宗, 1418-1450) is 40 Chi (尺) height and it was located in the west side of royal observatory, Ganuidae (簡儀臺). It is known that two kinds of size of gnomon were used during Joseon dynasty. Each size of 8 and 40 Chi of gnomon has 165.5cm and 828cm height of Pyo. The shape and size of 40 Chi gnomon are described in historical astronomical books of China and Korea, thus 40 Chi gnomon was restored as miniature ones recently. However, because of lack of resources, 8 Chi gnomon of Joseon dynasty has not been restored until now. We study and restore the actual size of gnomon in 8 Chi. Each size of Gyu and Pyo is 21.2 Chi and 8 Chi, respectively. The carved scales on Gyu make it possible to measure the length of the shadow cast in 2 millimeters. Heongyang (橫樑) installed on top of Pyo was designed to be propped by two dragons. We design a pond connecting waterways carved on the surface of Gyu. We also make a shadow-definer, Yeongbu (影符), which is a tool for enhancing the accuracy of Heongyang to measure the length of shadow cast.