To hold lubricant in a device without the deterioration of the lubricant caused by oxidation and to supply the necessary amount of lubricant from this section to a feed screw device when necessary.

A lubricant supplying device also serving as a seal 10 made of rubber or a synthetic resin containing lubricant and having a number of projections 11 contacted with the outer periphery of a screw shaft 1 in its inner surface is attached to a nut engaged with the screw shaft 1 of a feed screw device. Lubrication is performed by the gradual oozing-out of non-oxidized lubricant from the rubber or the synthetic resin contained in the lubricant over a long time.