In Nai-Gyung(內經), it is said that In-Yeong(人迎) means In- Yeong Maek(人迎脈), Gi-Gu m- eans Tson-Gu(寸口) or Maek- Gu(脈口), In-yeong, artery in the side of neck, is located before Yeong-Geun(瓔筋), called as Jok-Yang-Myung-Maek(足陽明脈),so the part of In-Yeong-Maek means In-Yeong-Hyul(人迎穴) of Jok-Yang-Myung- Wi-Gyung(足陽明胃經) showing the artery in the side of neck. The part of Tson-Gu-Maek is that of artery in Yo-Gol(橈骨), beating source of Soo-Tae-Eum-Maek (手太陰脈) Of In-Yeong-Gi-Gu-Maek, In-Yeong-Maek mainly consists of Yang(陽), Gi-Gu-Maek of Eum(陰), so In-Yeung means physical disease, short of extra Eum component. They said that if In-Yeong-Maek was more than Gi-Gu-Maek, it meant physical injury, while Gi-Gu-Maek was more than In- Yeo-ng-Maek, it meant internal injury. In-Yeong-Gi-Gu-Maek is the one to distinguish the external and internal, the inside and outside, Eum and Yang, but there is no definite classification method to distinguish it, also it is difficult to grasp the comparison of 1sung(1盛), 2sung(2盛), 3sung(3盛), interrelation with 12-Gyung-Rak(l2經絡), change of maek phases, so necessary to set up the clear definition for In-Yeong-Gi-Gu-Maek. For the two theories as to In-Yeong-Gi-Gu-Maek according to Nai-Gyung, the one is to diagnose the maek by comparing the In-Yeong-Hyul with Tson-Gu of Soo-Tae-Eum-Maek as Gi-Gu in the both sides of neck part, he other is to divide the left and right of Gi-Gu-Maek in to In-Yeong and Gi-Gu afterwards, but today it is difficult to compare and explain the medical theory afterwards owing to insufficient consideration of In-Yeong-Gi-Gu-Maek at Nai-Gyung. The diagnosis of In-Yeong-Gi-Gu-Maek at Nai-Gyung to distinguish the surplus and shortage of Eum and Yang up to now since Nai-Gyung has so important and diagnostic value as to grasp the exact meaning. Herewith, this researcher com-pared Nai-Gyung and medical theory afterwards, reported it to consider the fixed position and changing process of viscera and entrails arrangement of literatures introducing In-Yeong-Gi-Gu-Maek, examining the change of maek phases for normal maek and a-bnormal maek of In-Yeong-Gi-Gu-Maek, considering the 1 sung, 2 sung, 3 sung maek phases in In-Yeong-Gi- Gu-Maek. According to the above results, the conclusion was reached as follows. 1. In-Yeong as the outside indicates external disease(外感), showing the surplus and shortage of Yang symptom by having Boo-Maek(浮脈) as Py-ung-Maek(平脈), Gi-Gu as the inside indicates internal disease(內傷), showing the surplus and shortage of Eum symptom by having Chim-Maek(沈脈) as P-yung-Maek(平脈). 2. In Pyung-Maek of In- Yeong-Maek as Boo-Maek, g-radual sinking of more floated changing maek because of disease means the improvement of di-sease, in Pyung-Maek of Gi- Gu-Maek as Chim- Maek, gradual floating of more sunken changing maek because of disease means the improvement of disease. 3. They said that disease of Jok-Gyung-Rak(足經絡) is cha-nged to that of Soo-Kyung-Rak(手經絡) when Jo-Maek(躁脈) appears whether In-Yeong-Maek or Gi-Gu-Maek 4. With the exemples of 1 sung 2 sung 3 sung it was porned with the relation of Pyo-Ri-Soo-Jok(表裏手足). Therfore I can guess that this fact is a moment explained the Bu-You-Sa-Kyung(部有四經) mentioned in Nan-Gyung-18-Nan(難經 第18難). 5. I think that In-Yeong and Gi-Gu, as a diagnosis method which distinguish between the inside indicates internal disease and the outside indicates external disease, is required to study further researches.