The present invention discloses a patch for use in administration of an ionic medicine into a living body by infiltration of the ionic medicine into the living body through the living body surface without voltage application, characterized in that the patch comprises an ion-exchange membrane having a surface roughness (Rz) of 7 .mu.m or less at its part to be brought into contact with the living body surface and an ionic medicine impregnated into the ion-exchange membrane.