Human monitoring technology (HMT) is one of significant engineering tools for the development of human society and brought life innovations with the change of the times. In this paper, after the historical background of a HMT is mentioned briefly, a monitoring system for kindergartners, Kinder-Guardian system (KG), is introduced as an example of active studies in the health care field, which is a recent main market for the HMT. The KG system aims to both manage the health-activities of kindergartners and support the kindergarten staffs and utilizes an activity recognition technique based on a data clustering method. An innovation using the HMT including the KG cannot be created only by developing engineering technologies because a practical strategy suitable for all users is required with consideration of their explicit and implicit requests. This paper therefore presents a set of processes of the strategy that consists of the field exploration, a development of the clustering algorithm, a proposition of the system management, a prototyping of the hardware, and user evaluations in case of the KG.