PURPOSE: To provide a leg opening nail capable of providing sufficient drawing resistance strength by forming a sectional circular part from a contact point part of a long leg and a short leg in the head end direction so that the long leg becomes shorter and providing a processed deformed part on the other part of the long leg.

CONSTITUTION: The head end of a leg part 14 is inserted in a hole 33 of an article 32 to be installed which is accumulated on a construction material 31, the head part of a long leg 12 is hit and driven into the construction material 31 to fix the article 32 to be installed on the construction material 31. When the leg part 14 rectilinearly goes into the contruction material 31, a washer 15 makes contact with the article 32 to be installed and the projected head end part of the long leg 12 is further driven at the point of time when intrusion of a short leg 13 is stopped, the head end of the long leg 12 intruding into the construction material 31 pushes the head end part of the short leg 13 outside, bends it and moves it. Simultaneously, the head end part of the long leg 12 is bent to the side of the short leg 13, the head end part of the long leg 13 opens its leg in the construction material 31 and in the state where the article 32 to be installed is stabilized by an engagement head part 16 through the washer 15, the opened leg part displays drawing resistance strength.