This article analyzes Korea`s central agencies, which have been organized and reorganized to support presidential executive leadership since the foundation of the Republic. Each central agency has carried out the standardization of a core administrative function which is essential to the operation of administrative apparatuses, including policy planning and coordination, budgeting, organizing, staffing, legislation, public relations, central-local relations, control and performance evaluation, etc. The six decades of institutionalization can be characterized, based on the central agencies` proportion of the total administrative apparatus, into three phases: high (more than 35 percent, 1948-1961), middle (around 20 percent, 1962-2007), and low (about 10 percent, 2008-present). Regardless of the changing size and organizational configuration of the central agencies, however, their roles and influence as core executive apparatuses have remained largely unchanged, especially since the early 1960s. More than 67 percent, on average, of the heads and deputy heads of CAs have been former public servants, less than 18 percent have been former politicians, and about 15 percent have been former outside experts. This strong bureaucratic background has oriented Korea`s core executive policy direction significantly toward long-term, consistent, and plan rationality rather than short-term, flexible, and democratic responsiveness.