To provide a crosspiece supporting implement of a guard fence which is excellent in workability because a fastening operation can be performed by means of one fastening tool.

At least two locking portions 37 which abut on the side surface of a head of a polygonal bolt or the side surface of a polygonal nut for fixing the crosspiece supporting implement 3 to a support 1 via a bolt hole 32 so as to inhibit the turning of the polygonal bolt or the polygonal nut are protrusively formed on the inner surface-side periphery of the bolt hole 32 which is formed at a mounting portion 31 abutting on the support 1 of the crosspiece supporting implement 3. The locking portions 37 enable the polygonal nut to be fastened in a state of inhibiting the turning of the polygonal nut, or enable the polygonal bolt to be fastened in a state of inhibiting the turning of the polygonal nut. Thus, when the polygonal bolt is fastened in a state of making the side surface of the polygonal nut abut on the locking portion 37 in a state that the polygonal nut is arranged between at least the two locking portions 37 protrusively formed on the side of the inner surface of the mounting portion 31, the turning of the polygonal nut is inhibited so that the support 1 and the crosspiece supporting implement 3 can be efficiently fixed to each other.