A device for manufacturing dimethyl carbonate including a reaction section and a separation section is provided. The reaction section includes a first distillation column, a methanol supply device, a carbon dioxide supply device, a dehydrating agent supply device, and a side reactor. The methanol supply device is connected to the first distillation column. The carbon dioxide supply device is connected to the first distillation column. The dehydrating agent supply device is connected to the first distillation column. A feed nozzle of the side reactor is connected to a gas outlet of a top of the first distillation column. A discharge nozzle of the side reactor is connected to a recycle nozzle of the first distillation column. A catalyst is disposed in the side reactor. The separation section includes a second distillation column. The second distillation column is connected to a liquid outlet of a bottom of the first distillation column.