Firefighters are high-risk group for posttraumatic stress disorder because they are repeatedly exposed to traumatic events. In this study, we examined the effects of a short-term, intensive, Mind subtraction meditation-based healing program on the ruminations and posttraumatic stress disorder symptoms of firefighters. In 2019, we used a survey questionnaire to assess the intrusive ruminations of 80 firefighters at a firefighting headquarters before and after implementing the Mind subtraction meditation-based healing program and personal journals over a period of two nights and three days. The results showed that there was a significant decrease in posttraumatic stress disorder symptoms, from 32.40 (± 14.67) to 30.31 (± 13.76) among the male subjects, and a significant decrease in posttraumatic stress disorder symptoms, from 32.03 (± 13.31) to 27.33 (± 10.68) and intrusive ruminations, from 5.21 (± 7.32) to 3.41 (± 6.30), among the female subjects. In conclusion, the Mind subtraction meditation-based healing program was effective in reducing the posttraumatic stress disorder symptoms and intrusive ruminations of firefighters. Therefore, the Mind subtraction meditation-based healing program could be proposed as a mental health promotion program for firefighters.