A method for manufacturing an ion conductor including LiCB9H10 and LiCB11H12 is provided. The method includes mixing LiCB9H10 and LiCB11H12 in a molar ratio of LiCB9H10/LiCB11H12=1.1 to 20. An ion conductor including lithium (Li), carbon (C), boron (B) and hydrogen (H) is also provided. The ion conductor has X-ray diffraction peaks at at least 2θ=14.9±0.3 deg, 16.4±0.3 deg and 17.1±0.5 deg in X ray diffraction measurement at 25° C., and has an intensity ratio (B/A) of 1.0 to 20 as calculated from A=(X-ray diffraction intensity at 16.4±0.3 deg)−(X-ray diffraction intensity at 20 deg) and B=(X-ray diffraction intensity at 17.1±0.5 deg)−(X-ray diffraction intensity at 20 deg).