A water transmission device and a washing machine including the same. The washing machine includes a water transmission device configured to discharge water in a washing tub, wherein the water transmission device includes a filter case which is disposed under the washing tub and accommodates a filter, and into which the water in the washing tub is introduced, a pump case connected to the filter case and accommodating an impeller configured to suction the water in the filter case and discharge, a motor configured to rotate the impeller, a suction hole through which a side portion of the pump case facing a center of the impeller and a side portion of the filter case, and an outlet which is open downward from a lowest end inside the pump case and communicates with a water discharge pipeline.