Objective : The writer has come to see that a study of the Theory of Ministerial Fire of JuDanGae presupposes a study of earlier theories of fire. Therefore, I have analyzed and studied the theories of fire presented by medical doctors since "Nae Gyeong(黃帝內經)" Method : To begin with, I have studied the concepts of grand fire(壯火) and small fire(少火), imperial fire(君火) and ministerial fire(相火) in "Nae Gyeong", and have construed the meaning of human fire(人火) and dragon fire(龍火) by Wang Bing(王?), and fatty fire(膏火) by Sohn Sa-mak(孫思邈). Next, I have studied true fire(眞火) by Huh Sook-mi(許叔微) and true yang(眞陽) and pit fire(坎火) by Eom Yong-hwa(嚴用和), Theory on Right Kidney as the Gate of Life and Ministeiral Fire(右腎命門相火說) by Yu Wan-so(劉完素), and the reason why Jang Wan-so(張元素) asserted Theory of Three Burners as Ministerial Fire(三焦相火說). Result : I have understood the influence that the concepts of grand fire and small fire, imperial fire and ministerial fire in "Nae Gyeong"have exercised on the later medical doctors, and have also understood the physiological and pathological Fire that influences the human body. Moreover, I have seen that Fire, as discussed by scholars from Huh Sook-mi and Eom Yong-hwa to Yu Wan-so and Jang Wan-so, made great contribution to the later development of Theory of the Gate of Life, getting its entire picture in Eum Hwa. Conclusion : Seeing that the theories of Fire presented by medical doctors since "Nae Gyeong" and prior to JuDan-Gae had great influence on the later development of Theory of the Gate of Life, I have come to understand that along with Eum Hwa by Lee Dong-wan, they must precede a study of the Theory of Ministerial Fire of JuDan-Gae.