To provide a lubricant and a lubricant-circulating mechanism.

The lubricant comprises a lubricant base oil and liquid for vaporization cooling which is vaporized by frictional heat between movable faces to deprive the heat. The lubricant-circulating mechanism comprises a lubricant-accommodating means for accommodating a lubricant to be supplied between movable faces being in contact with each other, a supplying means for supplying the lubricant in the lubricant-accommodating means between the movable faces, a collecting means for collecting the lubricant supplied between the movable faces, and a lubricant-returning means for returning the lubricant collected by the collecting means to the lubricant-accommodating means, where the lubricant comprises a lubricant base oil and liquid for vaporization cooling, which is vaporized by the frictional heat between the movable faces to deprive the heat, and the liquid for vaporization cooling is condensed after vaporization and collected together with the lubricant by the collecting means. The mechanism comprises a homogenizer, installed in the lubricant- returning means, for redispersing the lubricant collected by the collecting means and the condensed liquid for vaporization cooling.