There is provided a catalyst for dimethyl carbonate synthesis which has a high conversion rate under the supercritical condition of CO.sub.2 and can be handled easily. The catalyst for dimethyl carbonate is obtained by loading SO.sub.4.sup.2- or PO.sub.4.sup.3- on a carrier composed of a compound having a solid acid site, and is used to produce dimethyl carbonate from acetone dimethyl carbonate and CO.sub.2 in a supercritical state. The component having a solid acid site is preferably one or more of ZrO.sub.2, Al.sub.2O.sub.3, and TiO.sub.2.