To provide a needle made of a flexible material and a leg guiding tool of a flexible needle for locking and holding various types of documents, a package of foods, or a tag after cleaning by a flexible locking leg.

In this staple, a needle group (10) formed of a plurality of flexible needles (4), (4) is arranged internally in a condition pressurized in a front end direction in a needle holding case (9) with vertical operation openings (7), (8) in its front end upper and lower parts. Groove depths of left and right leg point guide grooves (11), (12) arranged in a receiving base (13) part below the flexible needle (4a) in the very front end of the needle group (10) are differentiated, and one side is made deeper than the other, and left and right legs (2), (3) are always superimposed. Moreover, the superimposed part of the left and right legs (2), (3) is moved close to a heat source (20) arranged below the superimposed part by further weight of a pressing bar (18) for melting, thereby guiding penetration, welding, and locking of the flexible needle legs of the very front end side in an object (k) to be locked.