Lectures on Field Theory and the Many-Body Problem is a 23-chapter lecture series on the developments in the understanding of the structure and axiomatics of Field Theory, which has proved to be a most useful tool in the study of many-body problems. This book starts with a brief introduction to the TCP theorem, followed by a discussion on the gauge properties of the quantum electrodynamical quantities. The subsequent chapters describe the features and applications of unstable and composite particles to quantum field theory. These topics are followed by significant chapters on other aspects of the field theory, including the configuration space method, Wightman functions, vacuum expectation value, Pais doublets, time reversal in nuclear forces, and symmetry operations in quantum mechanics. This text also covers the ground state theory of many-particle systems and the many body problems at non-zero temperature. The last chapters explore the behavior of a Boson system, the polaron model, and the mathematical aspects of the Hilbert spaces. Physicists and researchers in allied sciences will find this book of great value.