[Problem] To provide: an anti-Myl9 antibody which can bind to Myl9 to inhibit the interaction between Myl9 and CD69 in a human body, or an Myl9-binding fragment of the antibody; and a pharmaceutical composition containing the antibody or the fragment. [Solution] A mouse anti-human/mouse Myl9 monoclonal antibody which has binding affinity for Myl9 was produced, and the sequences for complementarity determining regions (CDRs) of the mouse anti-human/mouse Myl9 monoclonal antibody were identified. Thus, a humanized antibody is produced, in which heavy-chain variable regions and light-chain variable regions respectively contain the CDR sequences of the mouse anti-human/mouse Myl9 monoclonal antibody.