The chloride ion conductor CH3NH3GeCl3 was characterized by DTA, Rietveld analysis of the powder X-ray diffraction, and Cl-35 NMR. The mobile ion at the high temperature phase was deduced to be a chloride ion, because a disordered perovskite structure at the Cl site was found by the Rietveld analysis. This disordered model was also confirmed by Cl-35 NMR. The mechanism of the ionic conductivity and the process to attain a conducting phase were discussed on the basis of the temperature dependence of the powder X-ray diffraction and the spin-lattice relaxation times of Cl-35 NMR.