PURPOSE: To lower temperature simply as well as make easier the removal of adhered mist for an electric dust collector by a method in which a large number of cold water-passing pipes are provided in a wide range in the neighborhood of the gas inlet of an electric dust collector for performing the cooling and rectification of incoming gas.

CONSTITUTION: An oily mist collector is made up by providing a large number of cold water-passing pipes in a wide range in the neighborhood of the gas inlet of an electric dust collector. For example, gas coming from the gas inlet 1 flows into the dust collector in an uniform flow state while being cooled when passing through the cooler and rectifier 2, during which mist is collected by the dust-collecting plate 3 and then discharged from the gas outlet 4. In the cooler portion, a large number of the finned water pipes 5 are provided in a wide range to make up of a rectifier for the flow of gas. The mist collected can be easily removed simply by heating it by a hot fluid, e.g., hot water, etc., flowing in the water pipes 5, whereby the viscosity of the mist is made smaller.