A solid lubricant supply system includes a solid lubricant supplier to receive and supply solid lubricant to a solid lubricant supplying target. A pair of first and second moveable planar electrodes is opposed to each other. The second moveable planar electrode is partially moved toward the first moveable planar electrode as the solid lubricant is consumed. A residual solid lubricant quantity detecting unit is provide to detect a quantity of the residual solid lubricant at a first stage, in which the residual solid lubricant quantity is below a given level, by detecting electric conduction between the pair of first and second moveable planar electrodes when the pair of first and second moveable planar electrodes contacts each other. The first moveable planar electrode is enabled to further move together with the second moveable planar electrode when it is contacted and pressed by the second moveable planar electrode.