Abstract: A lubricant supply device is to be fitted to a nut member engaging with a screw shaft through rolling members to supply lubricant to the screw shaft along with a relative rotational motion of the nut member to the screw shaft. The device comprises an application member, a lubricant storage member and a control device. The application member for applying the lubricant on the screw shaft has at least one tongue portion, which is capable of coming into contact with at least one of rolling-member running surface of the screw shaft. The number of the at least one tongue portion is identical with or larger than the number of the rolling-member running surface. The lubricant storage member supplies the lubricant to the application member. The control device controls an amount of the lubricant supplied from the lubricant storage member to the application member.