The object of the present invention is to provide an anti-canine PD-1 antibody or an anti-canine PD-L1 antibody, an agent for inhibiting binding between a canine PD-1 and a canine PD-L1 containing such an antibody, a method for inhibiting binding between a canine PD-1 and a canine PD-L1 comprising using such an antibody, and a gene encoding such an antibody. An anti-canine PD-1 antibody that specifically binds to a canine PD-1 consisting of the amino acid sequence set forth in SEQ ID NO: 1 and an anti-canine PD-L1 antibody that specifically binds to a canine PD-L1 consisting of the amino acid sequence set forth in SEQ ID NO: 6 are produced. An agent for inhibiting binding between a canine PD-1 and a canine PD-L1 containing such an antibody is also produced.
