The inventive machine (10) for ripping horizontal logs makes it possible to optimise and automate wood ripping for producing wood pieces having a predetermined cross section and comprises a main frame (20) provided with a pushing device (30) and an assembly of knives (40) comprising a first series (50) knives and a second series of knives (60) which are perpendicular with respect to each other and arranged on the main frame. The knives of each series (50, 60) are mounted with variable gaps obtainable by adjusting devices (70, 80). The pushing device (30) comprises a movable carrier (31) consisting of an assembly of flat horizontal pieces (32) and an assembly of profiles (35) which a movable with respect to each other in such a way that it is possible to axially push a log towards a knife blade and to push wood pieces out of the knife when the log is ripped.