To provide a supply device which is capable of supplying a suitable amount of a material to be ground with optimum timing to a burstone mill without necessitating the additional source of power such as electricity and the additional operation.

In the automatic supply device of the material to be ground, the exit aperture of a funnel which the material to be ground stores and the supply aperture of the burnstone mill do not communicate directly in the direction of gravity. A flow down channel of the material to be ground is formed by allowing a slide member to exist between the exit aperture of the funnel and the supply aperture of the upper mill, and the opening installed at the slide member and both of the apertures communicate with each other in the direction of gravity by interlocking the transportation of the slide member. Also, the supply device is driven by transmitting the power of the original driving section to conduct the rotational movement around the center axis of the turning lever as the rotation axis through the interlocking with the grinding of the turning lever to the slide member as the subordinate driving section using a predetermined power transmitting mechanism.