The purpose of this thesis is to use contactless measurement, to propose a robust system for heartbeats interval estimation that enables easy and stable health monitoring in the daily life. In recent years, cardiovascular disease is a major cause of death. Ballisto cardiogram (BCG), which records the mechanical activity of the heart, has been studied as a method provided an unobtrusive measurement. This technique provides the possibility of observing health status without causing any discomfort however, the signal quality can highly vary due to artifacts associated with breathing or postures of a user. Therefore, this study assesses the robust algorithm to estimate heartbeats interval from BCG signal measured by high-sensitive load sensors that mounted to bed legs. Three healthy subjects participated in the experiments that they lied on the bed with various postures. As a result, mean beat-to-beat interval errors were less than about 50 ms when subjects held in decubitus.