A control plate is provided at a preferred position in a storm overflow chamber. An inflow pipe, an intercepting pipe, and an outflow pipe are connected to the storm overflow chamber. A vortex flow type water surface control device for a draining device includes the overflow chamber, and a control plate arranged in front of an opening portion of the intercepting pipe opening to the storm overflow chamber. A relation (1) 0.5 D≦X≦0.7 D and 0.83 D≦Y≦1.5 D holds true, or a relation (2) 0.4 D≦X≦0.5 D and 1.0 D≦Y≦1.5 D holds true, where D represents an inner diameter of the opening portion, X represents a projection length of the control plate with respect to the opening portion, and Y represents a distance between the control plate and the opening portion. As a result, contaminants enter the intercepting pipe.