A nonaqueous electrolytic solution containing magnesium ions which shows excellent electrochemical characteristics and which can be manufactured in a general manufacturing environment such as a dry room, and an electrochemical device using the same are provided. A Mg battery has a positive-electrode can 1, a positive-electrode pellet 2 made of a positive-electrode active material or the like, a positive electrode 11 composed of a metallic net supporting body 3, a negative-electrode cup 4, a negative electrode 12 made of a negative-electrode active material 5, and a separator 6 impregnated with an electrolytic solution 7 and disposed between the positive-electrode pellet and the negative-electrode active material. Metal Mg, an alkyl trifluoromethanesulfonate, a quaternary ammonium salt or/and a 1,3-alkylmethylimidazolium salt, more preferably, an aluminum halide are added to an ether system organic solvent and are then heated, and thereafter, more preferably, a trifluoroborane-ether complex salt is added thereto, thereby preparing the electrolytic solution. By adopting a structure that copper contacts the positive-electrode active material, the electrochemical device can be given a large discharge capacity.