PURPOSE: To provide a nail capable of giving a large holding force without being loosened.

CONSTITUTION: A shaft part 12 is provided with bulging portions 13 having a circular cross section and streamlined contour. The bulging portion 13 is expanded gradually from the tip side to reach the maximum diameter portion 13b and gradually contracted at the contracted portion 13c behind the maximum diameter portion 13b. Thus, when this nail is driven in, fibers of a wood are not cut off. The wood makes intimate contact with the bulging portions and the periphery of the shaft part by the large stability to provide a large holding force. Also, since the bulging portion 13 has a circular cross section, the nail is not loosened even if the nail is turned by any shock or the like.