This book is concerned with the system biomechanics of bone adaptation through remodeling. The elegant bone structure in the living body is constructed by the collaborative activities of numerous bone cells interacting with the mechanical environment. The book provides a theory of bone remodeling to clarify the adaptation phenomena ranging from the cellular activities at the microscopic level to the skeletal change at the macroscopic level comprehensively. The multiscale mathematical modeling of bone adaptation explained in each section serves as a great source of concrete examples of in silico approaches. It will make a great contribution to readers interested in bone morphology and metabolism intellectually as an effective bridge between medical science and mechanical engineering. Such mathematical approaches to explore how the functionality of dynamical living systems are realized and maintained have a potential to facilitate graduate students and young researchers pioneering new frontiers of biomechanics.