To provide an outer package box for a bag-in-box, which prevents the attachment of a harmful insect or trash, produces less paper powder, does not cause swelling even if it is stacked, and has a superior waterproofness and a print aptitude.

The outer package box is a bristol style box composed of three members consisting of a main body (10) and a pair of side face closing members (20). The main body is made of a waterproof paper (1) formed by sticking together a waterproof non-coated cardboard (2), which is made waterproof by a rosin-based sizing agent, and a waterproof pulp cardboard (3), using a waterproof adhesive. The side face closing members (20) are made of a corrugated sheet (5).