Objective: To investigate the effectiveness and safety of continuous infusion of midazolam for the treatment of headache and/or nausea/vomiting in patients with brain tumors or cancer-associated meningitis. Methods: Patients who presented with headache and/or nausea/vomiting and underwent continuous infusion of midazolam from April 2005 to March 2021 were retrospectively analyzed. Results: Among 22 patients, 19 presented with headache and 14 with nausea/vomiting. The success rate of continuous infusion of midazolam for headache was 89% and that for nausea/vomiting was 78%. The mean number of vomiting episodes within 24 hours from the start of midazolam administration was 0.14±0.36, which was significantly lower than that from 24 hours before to the start of administration (1.43±1.60, P=0.015). Sedation was observed as an adverse event in five (23%) patients, but no patients developed respiratory depression. Conclusion: When conventional therapies are ineffective for headache and/or nausea/vomiting caused by brain tumors or cancer-associated meningitis, continuous infusion of midazolam may improve symptoms and should be considered as a treatment option.