To provide a punching tool, forming a through hole having a high aspect ratio.

In punching, a punch 1 is used for forming a through hole in a workpiece W. The punch 1 is provided with a substantially conical projecting part 11 at the tip of a punch body 10. When the punch body 10 is advanced into the workpiece W, in the case where the reaction force F applied to the side 11a of the projecting part 11 is non-uniform, the orthogonal component of reaction force F is about to bend the punch body 10 in the reverse direction to bending of the punch body 10 due to a difference from the axial component F2 of the reaction force F, whereby bending of the punch body 10 can be restrained to cause the punch body 10 to advance straight into the workpiece W. Thus, even if the through hole having a high aspect ratio is formed, the punch body 10 can be prevented from entering the workpice W as being bent to prevent breakage of the punch 1.