An automatic idle adjusting apparatus with a side shift function automatically adjusts the position of guides according to the kind of the workpiece provided and adjusts the distance between two workpieces processed using one metal mold. The apparatus includes two idle bases, a plurality of guides, and a plurality of three-axis moving means on the idle bases that move the guides. The three-axis moving means each comprises an X-axis guide block, a Z-axis guide block movably connected to the X-axis guide block, and a Y-axis guide block movably connected to the Z-axis guide block; one of the guides is movably connected to the Y-axis guide block. A shifting means is also provided that adjusts the distance between the idle bases.