A cryogenic system includes a space formed between a cooling stage of a cryocooler unit and an element to be cooled, and a thermal joint placed in the space, wherein the thermal joint is composed of a substance that has a melting point higher than the cooling temperature of the element to be cooled and that is in a liquid or gaseous state at room temperature and atmospheric pressure. The cryogenic system can achieve reproducible and excellent thermal contact at a cooling stage without applying a large mechanical stress to a cryocooler unit structure.