To supply gravels smoothly.

A gravel guiding route 3 is pivoted by a pivotal part 3b near its upper end, and can be rocked around the pivotal part 3b. Meanwhile, since the furthermore upper end side than the center of gravity of a bottom plate 3a is pivoted, the lower end side of the bottom plate 3a is lowered by the gravity, and supported in the abutting state on the peripheral surface of a lower side tire 1a. When the lower side tire 1a is rotated, the bottom plate 3a is rocked finely. Hereby, a scattering stone body 2 having any shape can be slid down along the bottom plate 3a without being stopped in the middle, and the scattering stone body 2 can be supplied smoothly between tires 1a, 1b.