To provide an epoch-making attachment pin easily and inexpensively manufacturable without requiring high processing accuracy, insertable and extractable by press-in into and from an insertion hole, and extremely superior in practical use.

This attachment pin is detachably inserted by press-in into the insertion hole 1, and is constituted so that a pin shaft 3 is formed in a meandering bending shape, and bending parts projecting in the different directions are formed in a plurality in the longitudinal direction on this pin shaft 3, and these bending parts are constituted in a press-in elastic pressing part 4 capable of being brought into pressure contact with an inner surface of the insertion hole 1 by bending elasticity of the pin shaft 3, and when bringing the respective press-in elastic pressing parts 4 into pressure contact with the inner surface of the insertion hole 1 by pressing the pin shaft 3 in the insertion hole 1, the pin shaft 3 is deformed, and the press-in elastic pressing part 4 is elastically pressed and abuts on the inner surface of the insertion hole 1 by return energization of the pin shaft 3.