PURPOSE: To manufacture a corrugated board bonded firmly with a plastic foam sheet by laminating integrally a soft plastic foam sheet with liners of the corrugated board through a plastic film.

CONSTITUTION: A corrugated board main body 1 is constituted of a paper inner core 2 and surface and back liners 3 and 4, and a soft plastic foam sheet 5 is applied to the surface liner 3. A heat fusion plastic film 6 is used as bonding medium, and said film 6 is laminated on both of the surface liner 3 and a plastic foam sheet 5. Polyethylene of superior resistance to water, resistance to humidity and resistance to chemicals and of superior elongation, resistance to tear and resistance impact is used for both the plastic foam sheet 5 and the heat fusion plastic film 6. As polyethylene has an extremely good bonding property with paper, especially craft paper, and as the foam sheet 5 and the film 6 are plastic of same material quality, said materials are easily bonded together, and the bonding force of the plastic foam sheet 5 is very powerful without generating any bonding unevenness or creases.