Boron neutron capture therapy is one of the radiation therapy using high intensity neutron up to 109 (cm-2 s-1). To evaluate prescript dose, it is important to separately detect thermal neutron flux and gamma dose. In our institute, Thermo-Luminescence Dosimeter (TLD) with the low sensitivity for thermal neutron to detect gamma ray dose, gold foil to detect thermal neutron flux have been used. TLD for detecting gamma ray dose at mixed field of intense neutrons can not be available because of discontinued products. Furthermore, we have successfully established the accelerator based neutron source for BNCT, it is desirable to develop new dosimeter instead of TLD. We propose the method using Glass Rod Dosimeter (GRD) with thermal neutron shielding. In order to evaluate thermal neutron fluence, the combination with GRD and boron nitride as a thermal neutron converter was also developed. Overview of new detection method and the results of performance test report in this paper. © 2013 Springer-Verlag.