To provide a pressure-floatation type scum separation-processing apparatus that makes after-discharge transportation be possible in an energy saving manner and in addition that can make separation step of scum and free water at transported point be at mostly simplified, by discharging by scraping-up the scum that floats in floatation-separation tank while dewatering it by a compression action.

Such an apparatus squirts collected scum-containing wastewater into a floatation-separation tank 2 together with water that is generated by a pressure type air dissolution apparatus 45 to float scum in the same floatation-separation tank 2 and discharges the floated-scum by a screw conveyor 17 that has a scraping-up screw 23 and a scum in-take port 20 equipped with a scum-guide 19, and rotary driving means 40 for scraping-up screw.