One of the aspects of the present invention is to provide a medical needle extending along a predetermined direction and having a vertical cross-section taken along a plane perpendicular to the predetermined direction of which cross-sectional area varies based upon a distance from a needle tip. The medical needle includes a plurality of maximal points where the cross-sectional area of the vertical cross-section is locally maximal, and a plurality of minimal points where the cross-sectional area of the vertical cross-section is locally minimal. The vertical cross-section at the maximal point closest to the needle tip has the cross-sectional area not less than those at any other maximal points.