Disclosed herein are a dust collection unit and a vacuum cleaner with the same. The dust collection unit includes: a container formed in an empty cylindrical shape and filled with water to a predetermined height above a lower wall, the container having an inlet and an outlet formed in an upper wall; and a water flow pipe whose top is joined to the inlet and whose bottom is submerged in water in such a manner that the bottom of the water flow pipe is spaced apart from the lower wall. The water flow pipe includes: a first pipe, a second pipe having a second inner diameter smaller than the first inner diameter and extending downwardly from the bottom of the first pipe; and a water channel formed in a body of the second pipe defining the second inner diameter in such a way as to fluidably communicate with the inside of the second pipe.