The purpose of the present invention is to provide an electrolytic solution having a high oxidative decomposition potential, whereby dissolution and deposition of magnesium proceed repeatedly and stably, using a non-nucleophilic alkoxide-based magnesium salt. The present invention relates to: (1) an electrolytic solution for a magnesium cell, obtained by mixing a compound represented by general formula (I), a Lewis acid, and a solvent; (2) an electrochemical device including the electrolytic solution, a positive electrode, and a negative electrode; and (3) a compound represented by general formula (I').