This study aims to investigate the formulation, development, and achievement of the motivation of aspiring headteachers in secondary schools in the Republic of Korea (hereafter, Korea). Because it is a sought-after position, aspiring headteachers undertake highly competitive and time-consuming processes to become headteachers. Educational leadership is important for school effectiveness and improvement. Understanding the motivation of aspiring headteachers will be useful to support educational leadership preparation. Thus, a qualitative study was conducted, and thirty-three headteachers were invited to semi-structured interviews to share their motivation from the start until they were appointed. In the findings, leadership capability was revealed as the inevitable reason for formulating motivation. When leadership capability was recognized, the participants were recommended to apply for the educational specialist role or to become the head of the education and research department, which are the typical pathways to becoming a headteacher in the Korean education system. In the development process, firstly, high social status was regarded as the extrinsic motivation (receiving), while financial rewards were not considered as extrinsic motivation. Secondly, being able to have a voice in the school and the education system emerged as a main intrinsic motivation (achieving). Lastly, most aspiring headteachers wanted to contribute to the improvement of the school and the education system; this motivation was linked to transcendent motivation (giving). Extrinsic motivation was easily shown on the surface, but intrinsic (achieving) and transcendent (giving) motivations were revealed as more meaningful motivations under the surface. Even though these motivations were genuine, educational leadership skills are considered essential to achieving transcendent motivations. This study suggests that it would be helpful for educational leadership preparation programs to be designed with an understanding of aspiring headteachers’ motivation.