Papermaking internal sizing agents and use thereof

Using the calcium carbonate as a filler, it is also used effectively papermaking internal sizing agent that can imparts sizing property, and formulation paper for internal sizing agent in a small neutral papermaking of either aluminum sulfate amount without using aluminum sulfate providing a paper or paperboard was collected using an object. As means for solving such a problem, in the papermaking sizing agents, as well as having a hydrophobic group and at least a portion is quaternized amphoteric copolymer of a cationic group as an active ingredient. Preferably, the amphoteric copolymer, the hydrophobic monomer (A), cationic monomer (B), and an anionic monomer (C) as essential, and the anion equivalent of the monomer (C) is the monomer ( are those obtained by polymerizing a monomer component is 0.1 to 90% of the cation equivalent of B), 4 Kyukaritsu of the cationic groups is 40 mol% or more. Paper or paperboard, comprising a papermaking internal sizing agent of the present invention.