[en] Through the fabrication of the Cu/SS and Be/Cu joint specimens, fabrication procedure such as material preparation, canning, degassing, HIP (Hot Isostatic Pressing), PHHT (Post HIP heat treatment) was established. The HIP conditions (1050 .deg. C, 100 MPa 2 hr for Cu/SS, 580 .deg. C 100 MPa 2 hr for Be/Cu) were developed through the investigation on joint specimen fabricated with the various HIP conditions; the destructive tests of joint include the microstructure observation of the interface with the examination of the elemental distribution, tension test, bend test, Charpy impact test and fracture toughness test. However, since the joint should be tested under the High Heat Flux (HHF) conditions like the ITER operation for verifying its joint integrity, several HHF tests were performed like the previous HHF test with the Cu/SS, Be/Cu, Be/Cu/SS Mock-ups. In the present study, the HHF test with Be/Cu/SS Mock-ups was introduced, which have three 80 mm x 80 mm Be tiles and each material depths were kept to be the same as the ITER blanket FW. And this test was performed to prepare the Qualification Program by ITER-O and the mock-ups have the same geometry with one for this program. Six Mock-ups fabricated with three kinds of interlayers such as Cr/Cu, Ti/Cr/Cu, Ti/Cu, which have been developed interlayer. According to the test conditions determined by the preliminary analysis with ANSYS code, test were performed under 1.5 and 2.0 MW/m² heat fluxes with 100-sec heating and 100-sec cooling. Two Mock-ups using the Cr/Cu interlayer survived under 1.5 and 2.0 MW/m² of heat fluxes up to larger number of cycles to a failure than expected ones. But others showed full detachment of Be tile during the screening test or 1st cycle under 1.5 MW/m² heat flux. From the above results, the best joining condition is to use the Cr/Cu interlayer but more study should be continued to improve the Be/Cu joining using other two interlayers