A polyisocyanate curing agent for a laminate adhesive, which comprises a hydrophilic polar group-containing polyisocyanate; a laminate adhesive excellent in heat-resistance, durability and adhesiveness to polyolefin film which adhesive comprises the above hydrophilic polar group-containing polyisocyanate and an active hydrogen-containing compound; and use of an adhesive comprising the above polyisocyanate curing agent and an active hydrogen-containing compound in film lamination.