PURPOSE: To obtain a plate shaped foamed body with a smooth surface by reduced motive power, by individually pressing flexible rail arranged to the inner surface of the opposed part of an upper mold conveyor by plural cylinders to carry out surface control.

CONSTITUTION: In an apparatus for continuously molding a plate shaped foamed body by introducing a foamable material M into the space between opposed surfaces of two endless conveyors 11, 12, a flexible rail 20 is arranged to the inner surface side of the opposed part of the upper mold conveyor 12 in the advancing direction of the conveyor and indidisually pressed by plural cyliders 30a, 30b, 30c... arranged so as to leave appropriate intervals to carry out the surface control of the upper mold conveyor 12. The pressure of the upper mold conveyor can be adjusted corresponding to the foaming pressure of the foamable material and, by gradually weakening said pressure face, the surface of a molded product can be gradually leveled and surface smoothness is obtained in extremely high preciseness.