It is an object of the present invention to provide an electrochemical device having an electrolytic solution having high current density, as well as high safety, where dissolution and deposition of magnesium progress repeatedly and stably. Furthermore, the present invention relates to an electrolytic solution for an electrochemical device, comprising (1) a supporting electrolyte comprising a magnesium salt, and (2) at least one or more kinds of the compound represented by following general formula (I) (wherein n represents an integer of 0 to 6, and n pieces of R1 and n pieces of R2 each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a halogenoalkyl group having 1 to 6 carbon atoms. A1 and A2 each independently represent —C(═O)—R3, —O—R5, —N(R4)—R3, —S—R3, —C(═O)—OR3, —O—C(═O)—R3, —C(═O)—N(R4)—R3, —N(R4)—C(═O)—R3, —SO2—R3, —N(R4)—SO2—R3, —O—B(OR5)2, —O—P(═O)(OR5)2, —CN, a monocyclic heterocyclic group, a group derived from cyclic acetal, a group derived from a cyclic carbonate ester, a group derived from a cyclic carboxylate ester).