Polymers are essential materials in modern medicine. Compared to general-purpose polymers, medical polymers are not significantly different chemically. However, since medical polymers must have high safety, their molecular weight, molecular weight distribution, and mixtures are precisely controlled. This controlled process ensures safety in the medical field. Many polymeric materials have been developed and commercialized for medical applications. The range of their properties is so broad that it is difficult to introduce all of them. This chapter introduces the essential properties required for medical polymers and the properties required for individual applications, followed by an introduction to the characteristics of primary medical polymer materials. This chapter also introduces the functions required for major medical applications and the innovations in polymer materials to realize them.