Introduction: We experienced a case of pneumatosis cystoides intestinalis with intra-abdominal free air following steroid therapy for an end-stage brain tumor. Case: The patient was a 67-year-old man. He had received surgery and chemotherapy for the brain tumor, but the disease progressed and his consciousness deteriorated. Eventually, he developed aspiration pneumonia and was hospitalized. His consciousness level remained poor even after the pneumonia improved. His survival prognosis was considered to be approximately 1 month, and he was transferred to a palliative care ward. After the transfer, administration of betamethasone 8 mg/day was started for the purpose of improving his level of consciousness. Temporary improvement was observed, and administration of this drug was continued with dose adjustments, as appropriate. Six weeks after the start of betamethasone administration, when his consciousness level again deteriorated, aspiration began to recur. Chest X-rays, obtained to assess pneumonia, showed intra-abdominal free air. Pneumatosis cystoides intestinalis was confirmed by computed tomography. He had few abdominal symptoms, and was managed conservatively. He died of respiratory failure. Conclusion: Pneumatosis cystoides intestinalis is mostly secondary, and steroid therapy is considered to be one of the causes. But follow-up observation is often conservative, and judgment of discontinuation of steroid needs to be made in consideration of its effect and prognosis is there.