We treated the persistent ruminative vomiting of a 13-year-old autistic boy by using a behavioral and psychopharmacological approach in a closed ward. Before the interventions, the patient had lost about 10kg of body weight due to very high-frequency ruminative vomiting. Together with psychopharmacological trials, the psychiatric treatment included a combination of a behavioral approach and food regulation that emphasized food restrictions, and we provided regular light meals. There was a considerable reduction of the ruminative vomiting and 2kg weight gain was achieved during the admission. These therapeutic gains were maintained at the 4-month follow-up assessment and the vomiting symptom reached a near-zero level and the weight loss were recovered by about 8kg. The issues related to the treatment approaches for ruminative vomiting with autism are discussed.