PURPOSE: To uniformly apply paste to the apexes of corrugations without generating air jet or noise by moving a magnetic member toward a lower roll by the attraction force due to a magnetic field generator to press corrugated cordboard to the lower roll.

CONSTITUTION: The corrugated cardboard molded by an upper roll 1 and a lower roll 2 is transferred to a pasting apparatus and the apexes 3a of the corrugations thereof are coated with paste 6 by a pasting roll 9. Subsequently, liner paper 4 is supplied so as to come into contact with the apexes 3a of corrugations through a press roller 5 to prepare single-sided corrugated cardboard 5. During preparation, a magnetic field is generated in a magnetic field generator 13 by the supply of a current and attraction force acts on a magnetic member 11 by this magnetic field to energize the magnetic member 11 so as to allow the same to approach the lower roll 2. Therefore, the corrugated cardboard 3A molded by both rolls 1, 2 to be transferred toward the pasting apparatus 7 can be pressed to the lower roll by the approach and moving force of the magnetic member 11 and no levitation is generated in the cardboard 3A and, therefore, the paste 6 is uniformly and pref. applied to the apexes 3a of corrugations.