A ram guiding apparatus 1 of a machine tool is incorporated in a portal type machine tool 2 and provided with a cross saddle 5 that is cross-like in shape, as seen in a side view of the machine tool 2, provided so as to be freely movable in the horizontal direction along a horizontal cross beam 4. The cross saddle 5 has a box 18, both upper and lower faces thereof being open, in a front side of a horizontal part, wherein a first linear guide 21, a second linear guide 22, and a third linear guide 23, respectively serving as linear guides in the box 18 for a ram vertical movement, guide the ram 9 so as to be freely movable only in the vertical direction.