In this proposal, we would like to suggest inelastic neutron scattering measurement on a single-crystal sample of a frustrated antiferromagnet CuFeO2 under applied magnetic field up to 13.5 T using LET. Magnetic excitations in CuFeO2 have recently attracted increasing attention because of the discovery of a dynamical magneto-electric (ME) coupling, i.e., ¿electromagnon¿, in the collinear four-sublattice (4SL) antiferromagnetic ground state. Because CuFeO2 also exhibits collinear commensurate magnetic orderings in magnetic field induced phases, we anticipate that the electromagnet excitations are also observed to emerge in the field induced phases. The main purpose of this experiment is to observe the magnetic excitation spectra in the field induced collinear five-sublattice (5SL) phase, which shows up in the magnetic field region of 13 T < H < 20 T, below 9 K.