The present invention relates to an electric dust collector wherein collector cell plates of the electric dust collector are spaced from and stacked on each other, thereby electrically collecting electrified contaminants; the cell plates are distinguished at small widths, thereby configuring an independent collector cell assembly; multiple collector cell assemblies are overlapped and configured toperform dust collection; the collector cell assemblies are configured to be selectively coupled according to the situation on the spot where a dust-collecting facility is to be installed; accordingly, dust collection conforming to the situation on the spot is possible, thereby improving the dust-collecting efficiency; cleaning is easy, and maintenance is convenient; the user can selectively modify the collector cell assemblies according to the situation on the spot; and, when the collector cells are manufactured, defects resulting from erroneous component insertion can be prevented, thereby improving the productivity, the electric dust collector being characterized in that cell plates (400) are provided at small widths, spaced by spacers (500) that follow the same specification, and stacked to have a single gap; both ends of the cell plates (400) are finished by end plates (300), and the end plates (300) on both ends thereof are fastened by angles (310), thereby configuring a single independent first collector cell unit (210); different independent second and third collector cell units (220, 230) are independently configured so as to have small gaps that are different from the cell plate gap of the first collector cell unit; and one of the collector cell units or at least a plurality of multiple cell units are fitted and coupled to a dust collector housing (100), thereby constituting the electric dust collector.