Background: Boron neutron capture therapy (BNCT) is tumor-selective particle radiation and theoretically efficacious especially for tumors with infiltrative nature, such as glioblastoma (GBM). The aim of this study is to assess safety and efficacy of accelerator-based BNCT (AB-BNCT) using cyclotron-based neutron generator, BNCT30, and ¹⁰B-boronophenylalanine (borofalan(¹⁰B)) agent, SPM-011, in patients with recurrent malignant gliomas, chiefly GBM. Methods: The multi-institutional open-label, phase II clinical trial for recurrent 27 cases of malignant gliomas (MG) (24 cases were GBM) was conducted with above mentioned AB-BNCT system, using 500mg/kg of SPM-011 (study code, JG002). The patients were enrolled from February 2016 to June 2018. The inclusion criteria are bevacizumab-naïve MG, recurrent after standard treatment composed of XRT and chemotherapy with TMZ. Neutron-irradiation time were determined not to exceed to 8.5 Gy-Eq for scalp dose which was decided by preceding phase I trial. Primary endpoint was 1-year survival rate and secondary ones were median overall survival (mOS), median progression free survival (mPFS) and so on. The results were compared to previous Japanese domestic bevacizumab trial for recurrent GBM (JO22506) which had the similar inclusion criteria with JG002. Results: 1-year survival rate and mOS of recurrent GBM cases in JG002 was 79.2% (95% CI:57.0-90.8) and 18.7 months (95% CI:12.9-23.4) (data cutoff = 20 Jun 2019) respectively, while those of JO22506 was 34.5% (90% CI:20.0-49.0) and 10.5 months (95% CI:8.2-12.4), respectively. Median PFS of JG002 and JO22506 were 0.9 and 3.3 months, respectively. Most important adverse event in JG002 was brain edema. 21 out of 27 cases were treated with bevacizumab after progress disease. Conclusions: AB-BNCT demonstrated acceptable safety and prolonged survival for recurrent MG chiefly GBM. AB-BNCT might produce brain edema somewhat after the treatment, which might be the unavoidable adverse event of re-irradiation for recurrent MG, however that seemed to be controlled with bevacizumab. Clinical trial information: JapicCTI-194742.