Provided are anti-PAD4 antibodies having excellent properties and an excellent method for treatment of RA. Used are anti-PAD4 antibodies that specifically bind to an epitope containing positions 345, 347, and 348 of PAD4. These anti-PAD4 antibodies may inhibit the citrullination activity of PAD4. In addition, these anti-PAD4 antibodies may have a KD (M) of 9.0 × 10 -9 or less. Optionally, the anti-PAD4 antibody and a TNF± inhibitor are used in combination.