Disclosed is a gluing device including a reservoir tank of liquid glue; an applicator roll partially immersed in the liquid glue; a doctor roll for adjusting a thickness of the liquid glue adhered to the applicator roll to become uniform; and a pair of glue dams for regulating a width of the liquid glue adherable to the applicator roll. The gluing device is configured to apply the adhered liquid glue on the applicator roll to a corrugated medium of a corrugated paperboard sheet. Each of the glue dams includes a pair of dam units located in spaced-apart relation to each other in a width direction of the applicator roll. The pair of dam units are configured to form a glue-uncoated region interposed between the pair of dam units on an outer peripheral surface of the applicator roll so as to correspond to a trimming region of the corrugated paperboard sheet.