To date, several polymer-derived ceramic fibers have been developed all over the world, out of which SiC fibers synthesized from polycarbosilane and their derivatives have achieved highest heat resistance and show excellent mechanical properties. Their use in ceramic matrix composite materials has resulted in high-temperature stability and light weight, which show great promise in next-generation applications, such as aerospace engines. This book presents polymer-derived ceramic fibers from a historical viewpoint; basic information about them, such as production process, fine structures, and physical properties; their applications; and prospects of future inorganic fibers.