This study analyzed Sejong's life philosophy and great achievements in terms of a macro and integrated standpoint from the perspective of spectrum leadership, and the main findings are as follows. First, King Sejong was born as the third son of King Taejong and rose to power against all hardships; once he became the king, he laid the foundation for a first-rate nation by creating the Hunminjeongum, Korean language, and although he preferred virtue to the rule of law, he was strict against corrupt officials who exploited the people. Second, he was a good listener: he was wary of arbitrary decisions, and valued pure reason. He also focused on recruiting talented people, even appointing Jang Young-sil, a former vassal. He also strengthened organizational cohesion by leading an exemplary life himself, esteemed creative problem-solving skills, and rewarded those who remained loyal to the king by remunetaing them reasonably. Third, King Sejong was attentive to his subjects' grievances, famine, and plagues. In addition, he was a humane person, and in judging criminals, he was as attentive to the public opinion as he followed strict to the law. Besides this, he also enjoyed socializing over tea; falconry; and bathing in hot springs, where he spent time recuperating his body and mind from fatigue.