This text book on QUANTUM MECHANICS covers all the basic concepts of the subjects and the applications of quantum mechanical principles in various physical problems. This would meet the requirements of an undergraduate student who studies a course on quantum mechanics. The sequential development of the content helps the students to understand the subject without any difficulty. This book has divided into nine chapters and the entire content can be taught in a two-semester course. The subject is introduced from its basic principles in a simple and sequential manner. • The principles are applied to solve a large number of physical problems and detailed mathematical derivations are given. • An interactive approach is used while developing the contents of the text book. • Care is taken to keep a balance between mathematics and verbal explanations. • Comments and explanatory notes are given where ever necessary. • A large number of problems are solved at the end of each chapter. • Practice problems and review questions at the end of each chapter.