PURPOSE: To form a uniform lubricous film by giving to a contour of a sealing frame on a supply side of a band material a smaller width than in front of the supply side with respect to an apparatus for applying surface pressure in a style that a sealing frame is pressure loaded in the direction toward a pressing belt.

CONSTITUTION: The sealing frame 1 comprises a frame body 2 and a piece of sealing stripe 3, and the sealing frame 1 is movably supported in a groove 4 of a pressing plate 5 and supported by the pressing belt 6 with the piece of sealing stripe 3. The sealing frame 1 confines a pressure cushion 7 filled with pressure medium together with the pressing plate 5 and the pressing belt 6. When the lateral beams on the supply side and discharge side for product have the same width, a gap appears between the sealing frame and the pressing belt at the time of discharge and the pressure medium flows out. When the lateral beam 14 on the supply side of the sealing frame 1 has a width larger than that of the lateral beam 15 on the discharge side, the gap of these sealing frames is avoided. Thereby, a circular sealing with sufficient pressure cushioning is secured, and generation of a uniform lubricous film is promoted through an obtained uniform operational pressure.