In this proposal, we would like to propose to perform neutron diffraction experiments on the powder samples of the frustrated antiferromagnets AFeO2 (A=Cu and Ag) using WISH. In CuFeO2, several novel cross-correlated phenomena, such as magneto-electric multiferroics and spontaneous spin-lattice coupling phenomena have been recently reported. However, the detail crystal lattice structure including super structure associated with these phenomena has not been clarified. As for AgFeO2, neither the magnetic structure nor the crystal lattice deformation have been studied so far. The main purpose of the experiment is to identify the magnetic phase transitions including the magnetic structures and the lattice modulations of AFeO2 (A=Cu and Ag) using WISH. In this experiment, we require the machine time of total 4 days.