A splitting, a cutting or a cutting-splitting machine with a safety mechanism for limiting access to a splitting knife, wherein the machine has a frame, to which a movable and optionally left-right adjustable conveyor belt is mounted, said conveyor belt being rotatable around a fulcrum in a bottom part of the conveyor belt and has an approximately vertical transport position and a working position at an angle relative to the ground where the machine is located, characterized in that the machine has: - a movable protective plate provided at least on one side of the conveyor belt, the protective plate arranged to cover at least part of the machine frame and part of the conveyor belt side, wherein the protective plate is provided with at least one groove, cut-out, guide or a similar structure, along which a screw, a bolt, a welded or screwed plug with a cotter-pin, a cylinder or a similar element mounted on the side of the conveyor belt and/or on the machine frame, - a connective lever or a handle connected to the protective plate and an axle of the protective plate, which is located in the bottom part of the conveyor belt frame, where said fulcrum is located, wherein the connective lever is on both ends provided with a suitable element arranged to enable rotation in the mounting on the protective plate or a holder or an axle of the protective plate, - the axle of the protective plate mounted in a manner that enables movement of the protective plate together with movement of the conveyor belt due to the connective lever, wherein the connective lever is arranged to move preferably from an approximately horizontal position in a transport position to an approximately vertical position in a working position, wherein the screw, nut, plug or a similar element is arranged to move along the cut-out, groove, guide or any other suitable structure on the protective plate from one extreme position near the machine frame towards the second extreme position at the opposite end of the cut-out, groove, guide or any other structure. - a movable protective plate provided at least on one side of the conveyor belt, the protective plate arranged to cover at least part of the machine frame and part of the conveyor belt side, wherein the protective plate is provided with at least one groove, cut-out, guide or a similar structure, along which a screw, a bolt, a welded or screwed plug with a cotter-pin, a cylinder or a similar element mounted on the side of the conveyor belt and/or on the machine frame, - a connective lever or a handle connected to the protective plate and an axle of the protective plate, which is located in the bottom part of the conveyor belt frame, where said fulcrum is located, wherein the connective lever is on both ends provided with a suitable element arranged to enable rotation in the mounting on the protective plate or a holder or an axle of the protective plate, - the axle of the protective plate mounted in a manner that enables movement of the protective plate together with movement of the conveyor belt due to the connective lever, wherein the connective lever is arranged to move preferably from an approximately horizontal position in a transport position to an approximately vertical position in a working position, wherein the screw, nut, plug or a similar element is arranged to move along the cut-out, groove, guide or any other suitable structure on the protective plate from one extreme position near the machine frame towards the second extreme position at the opposite end of the cut-out, groove, guide or any other structure.