A monoclonal antibody, which recognizes at least two amino acids among amino acids located at position 69, position 79, position 81 and position 102 of human midkine, has been found to have excellent reactivity with and excellent neutralizing activity against human midkine. Moreover, the activity of suppressing the proliferation of tumor has been observed in the antibody having excellent neutralizing activity. The use of the antibody of the present invention makes it possible to treat cancer effectively and to detect or purify midkine efficiently.
