The research to date on those who were appointed as grand secretaries in the Ming Dynasty Chancellery (neigeguan 内閣官) has focused on the process of piaoni 票擬 of which they took charge, evaluating them as personal scribes serving the emperors who held absolute authority. However, piaoni was not the only duty of neigeguan, as pointed out in the analysis done by the author of the present article regarding the process of jingyan 經筵 up through the Jingtai 景泰 Era (1450-57), which led to the conclusion that neigeguan managed the daily affairs of the emperors through jingyan. Here, the author analyzes the origins of one more important duty of them, the education of the heirs apparent, arguing that this activity is the key to understanding the whole raison d’être of neigeguan. The article begins with the circumstances surrounding the absence of an heir apparent during Jingtai Era and traces the response to such a situation within the Ming Dynasty bureaucracy. Then the author turns to the course of events from the debilitating illness suffered by Emperor Jingtai up to the re-enthronement of Emperor Yingzong 英宗 (Emperor Zhengtong 正統/Tianshun 天順), understanding it as a time when the whole bureaucracy was calling for the appointment of an heir apparent. The problem surfaced on the day that the Emperor was no longer able to “appear and preside over the Court” (shichao 視朝). The court ceremonies of the Ming Dynasty, especially the early morning audience (zaochao 早朝), were occasions for the emperors to approve petitions submitted from the various government bureaus concerning administrative action. Therefore, the call to install an heir apparent was to insure that whenever the emperor was unable to preside over the Court, the heir apparent would be substituted, in order not to delay administrative affairs. Next, the author explains the institutionalization of the education of heirs apparent during the Tianshun Era (1457-64) and examines the process by which the duties of tutors of the heirs apparent (tidiao 提調 and tidu 提督) were assumed by neigeguan. It was at this time that responsibility for scheduling and determining the topics of tri-monthly imperial lectures (jinjiang 進講) was once more assumed by neigeguan, which led to the firm establishment of a system for educating heirs apparent. Consequently, upon the debilitating illness of Emperor Yingzong, suspension of the morning audience was avoided by the appearance of his heir apparent in his stead. The author concludes that during the Ming Period as a whole, the bureaucracy expected the emperors to at least appear at their early morning audiences and tri-monthly lectures, and it was neigeguan who were responsible for making certain the emperors performed those duties. It is for this reason that neigeguan should be viewed as assuming the most critical tasks in ensuring that the Ming administrative hierarchy, with the emperor at its pinnacle, functioned properly.