To provide an Li-ion conductor which has high Li-ion conductivity applicable to an electrochemical element as an Li-ion solid electrolyte.

The Li-ion conductor contains at least Li, AL, P and Si, and when calculated in terms of respective oxides, respective contents (mol%) of them are as follows: the Li content in terms of Li2O ranges from 2 to 38 mol%, the AL in AL2O3 3 to 7 mol%, the P in P2O5 5 to 15 mol%, and the Si in SiO2 45 to 90 mol%. In addition, the Li-ion conductor may contain a crystal phase of an olivine type or a Nasicon type compound as a part of its constituents.