This study aims to describe the effectiveness of the application of a confined space special work permit procedure for welding the main tank of the fuel truck at PT. Mangala Usaha Manunggal. Confined space has a very high potential hazard that can endanger the safety of someone who enters it, so prevention efforts are needed to avoid work accidents, one of which is the application of a special work permit to work in a confined space. This type of research is descriptive research with qualitative methods. Data collection was done through observation and interviews. Informants in this study consisted of: 1 head of the HSE department, 1 HSE executive, 1 head of the PLANT department, and 1 work supervisor. Data analysis based on KEP No. 113/DJPPK/IX/2006, and SOP-00-HSE-008 special work permit for PT. Mangala Usaha Manunggal. The process of working in confined spaces includes the implementation of procedures for the confined spaces system in which every work in a confined space must have a person in charge, working employees, stand-by person and safety officer who gives permission to work in the confined spaces area. The results of this study indicate that the amount of conformity between regulatory standards and existing conditions at the work preparation stage is 86%, at the work implementation stage is 81%, at the closing/completed work stage is 100%, then the overall value obtained is 89% so that these results indicate the level of achievement in the level of effectiveness included in the criteria of "fairly effective". Conclusion from The application of special work permit procedures for confined spaces work at PT Manggala Usaha Manunggal has not been fully in accordance with KEP No. 113/DJPPK/IX/2006, but has been "effectively enough" carried out according to company procedures. This is because the company has not certified personnel/officers in particular (intermediate and primary) for work in confined spaces, the company has not provided SCBA (self contain breathing apparatus), the company's Rescue Plan has never conducted a first aid simulation for victims in a confined space, the company does not yet have certified first aid personnel as required in the guidelines.