For developments of innovative nuclear reactors, strong demands exist for the improvement of the accuracy of the neutroncapture cross sections of minor actinides (MAs) and long-lived fission products. We have constructed a Ge-spectrometer using the Accurate Neutron-Nucleus Reaction measurement Instrument (ANNRI) in the J-PARC materials and life science experimental facility (MLF). Preliminary neutroncapture cross sections of Cm-244 and Cm-246 were obtained in the neutron energy range from 1.0 eV up to 300 eV.