We present the status of the COsmic BAckground Neutrino Decay search (COBAND) experiment. The signal of the cosmic background neutrino decay is identified as a sharp off at high energy end in a far-infrared region ranging from 15meV to 30meV in the energy spectrum of the photons from the space. The COBAND experiment will be done as rocket and satellite experiments in order to detect the far-infrared photons from the space. For a photon detector of the COBAND experiment, we are developing the Superconducting Tunnel Junction (STJ) detector. We will use a combination of the diffraction grating and the array of Nb/Al-STJ pixels for the rocket experiment, and use Hf-STJ as a micro-calorimeter for the future satellite experiment. The present status of the COBAND experiment is reported in more detail.