This paper analyzes the trends and transitions in debates regarding medical expense subsidies for Nanbyo/Rare and Intractable disease, from the Outline of Intractable Disease Measures（OIDM）compiled in 1972 to the Act on Medical Care for Patients with Intractable Diseases（AMCPID）enacted in 2014. The research method regarding the enactment of the AMCPID was to chronologically analyze the minutes of government council meetings in the 2010s. The method regarding the debate from the compilation of the OIDM until 2010s was to analyze the minutes of the National Diet, using quantitative text analysis techniques.

The results of the analysis show the following three points.（1）Under the influence of the advances in the medical, welfare, and nursing care systems, the emphasis on the concept of Nanbyo has shifted from unknown causes to rarity.（2） The basis for providing subsidies has shifted from public relief to the difficulty of the disease and the universality of its onset.（3）As the legal basis for subsidies has been enacted considering the comparison with other systems, there is also a strong demand for balance and fairness with other systems in terms of requirements for subsidies, requiring objective standards.