目標：本研究主要探討職業安全衛生法適用範圍之意義與變革，發現問題，並予檢討。方法：本研究採用文獻分析法、內容分析法與歷史研究法，蒐集歷年法規與行業標準分類沿革相關文獻，透過時間序列分析、比對，歸納適用範圍修正原因與方向。另採比較分析法，與勞動基準法適用範圍比較。結果：本法適用範圍可區分為4期，即「適用範圍4階段論」。第1階段係草創期，當時僅明定適用5大行業。第2階段為擴大期，適用範圍由5大行業擴大為14種事業。第3階段為改革期，刪除適用行業標準分類之規定，使適用範圍與行業標準分類脫鉤。第4階段為成熟期，適用範圍由14種事業，修改為「適用於各業」。結論：勞工安全衛生法從最初適用於5大行業，修正為職業安全衛生法「適用於各業」，可謂劃時代進步。除具體回應國際公約對「人人享有安全衛生工作環境」之宣示，更象徵我國職業安全衛生標準與各重要國家接軌的決心。新法施行後，當可樹立我國職業安全衛生新標竿。

Objectives: The aims of this study were to explore the meaning and scope of and amendments to the Occupational Safety and Health Act, and to identify issues of concern. Methods: We utilized literature review, content analysis and historical research to review the evolution of regulations and classifications of the industrial standards of safety and health. Time series analysis and matching were also used to evaluate the generalization, reasons for, scope and direction of amendments. This study also used the analytical method to compare the applied scope of the Labor Standards Law. Results: The scope of the laws that have been applied in Taiwan can be divided into 4 periods, known as the ＂the 4-stage application scope＂. The first phase was the initial period of implementation of the law, which was applied to only 5 major industries. The second phase was the expansion of the Act to include 14 types of industries. The third phase was reformation of the law by removing specific provisions for standard classifications applicable to industries, and removing links between standard classification and the scope of the law applicable to them. The fourth phase was the stage of maturity of the Act, and expanded the scope from the original 14 industries to ＂applicable to all industries＂. Conclusions: Progress from the Labor Safety and Health Act for 5 major industries to the Occupational Safety and Health Act for all industries has been significant. The evolution of the Act has been a reflection not only of specific responses to the International Convention for ＂safe and healthy working conditions for all＂, but also symbolizes our determination to link our occupational safety and health standards to other countries. In the future, the new law may require additional modification in order to establish new benchmarks for occupational safety and health in Taiwan.