Abstract: In a linear guide apparatus having an axially extending guide rail including a first loaded ball rolling groove formed in an inner lateral side of the guide rail; a slider fitted loosely inside the guide rail and including a second loaded ball rolling groove formed in an outer lateral side of the slider and a circulator with an unloaded ball circulating passage which extends axially; and a plurality of balls rolling along the first and second loaded ball rolling grooves via the unloaded ball circulating passage to support the slider moving axially relative to the guide rail, the linear guide apparatus further has a lubricating mechanism which includes a lubricant feed hole formed in a bottom of the guide rail and a lubricant injection port of the circulator to communicate with the unloaded ball circulating passage, the lubricant injection port connecting the lubricant feed hole at a predetermined position of the slider relative to the guide rail.