This book is a systematic introduction to astrometry and celestial mechanics. It consists of five parts: Observational astrometry, theoretical astrometry, basics of celestial mechanics, orbital dynamics, and rotational dynamics. The book is unique in various aspects. First, it discusses astrometry and celestial mechanics in a single and unified manner. Second, it stands on not the Newtonian but general relativistic viewpoints. Third, it explains both the orbital and rotational motions of celestial bodies. Fourth, it conforms to the latest International Astronomical Union (IAU) resolutions and Conférence Générale des Poids et Mesures (CGPM) rules. Lastly, its historical topics, ample exercises, and detailed model answers stimulate readers. The appendixes also provide various tables of constants, basic mathematical formulae, descriptions of symbols used, lists of technical abbreviations and model solutions to exercises.
 
The book is intended for undergraduate students of physics or astronomy. Further, it serves as a pocket reference also useful for professional scientists.
 
The basis of the English translation of this book from its Japanese original manuscript was done with the help of artificial intelligence. A subsequent human revision of the content was done by the editor and authors.