The present invention provides a water-flowing mechanism in a wet type electrostatic precipitator that can stably and quickly form a water film on a dust-collecting plate even at the beginning of the operation and that has an excellent adjusting function of a supplying flow-rate of washing liquid. The present invention includes a dust-collecting plate, a washing liquid supplying source to wet the dust-collecting plate, and a cylindrical member that is opened according to the shape of the upper end face of the dust-collecting plate and into which the washing liquid supplying source is inserted, wherein the horizontal cross-section of the dust-collecting plate is formed in a corrugated shape, and the lower opening of the cylindrical member is formed in a corrugated shape according to the dust-collecting plate.