Thermal nano-imprinting is a useful method for making nano-patterns onto various polymer surfaces. The clarification of the relationship between polymer properties and moldability of nano-patterns is very important in order to form the nano-patterns with very high precision and without defects. So far, reports on the moldability of nano-patterns have discussed in terms of bulk polymer properties. The objective of this research is to characterize the relationship between a surface glass transition temperature and moldability of nano-patterns by thermal nano-imprinting. The surface glass transition temperature of a polymer in nano-patterns was estimated by a model measuring method. By the scanning probe microscope measurement, it was supposed that the glass transition temperature in a nano-pattern is lower than that of a bulk polymer and declines as the pattern size becomes fine. As a result of nano-imprinting, to keep a surface glass transition temperature higher than a mold releasing temperature was required in order to make nano-patterns with very high precision and without defects.