To provide a water-resistant corrugated board provided with high water resistance and with excellent recycling properties by using a water-soluble starch paste as a bonding paste and applying water-repellent treatment on the surface of liners and the surface of an inner core.

For this water-resistant corrugated board 6, a corrugated board 4 prepd. by bonding a liner 2 on at least one face of a wave-shaped inner core 1 with a starch paste 3 is provided and water-resistant coating film 5 are formed on the surface of the inner core 1 of the corrugated board and the surface of the liner 2. In addition, an immersion liq. for the water-resistant corrugated board is an emulsion liq. comprising an aqueous resin emulsion and/or a rubber latex, a water-repellent agent emulsion and water and the viscosity of the emulsion liq. is adjusted to at most 100 cps. In addition, in the method for producing the water-resistant corrugated board, the corrugated board is immersed into the immersion liq. for the water-resistant corrugated board for a time being at most 10 min and the corrugated board taken out from the immersion liq. is dried by heating at 100-150°C.