Biomass cutting shears intended for a compaction or baling apparatus, comprising an inner blade holder (3) and an outer blade holder (4), with fixed or interchangeable semi-circular blades (5) and (6), said inner blade holder (3) being mounted inside the outer blade holder (4), so that the blades (5) and (6) cross one another when moved by the cylinders (7). The assembly comprised by the blade holders (3) and (4) and the cylinders (7) is mounted on an anchoring structure (8) connected to the end side of the machine (2) the blade holders (3) and (4) slide sideways inside the structure (8), which includes stop elements (9) for limiting the travel thereof. In addition, the invention includes a funnel (10) for the introduction and centering of the bale, as well as travel sensors (11). Furthermore, plates have been provided between the blade holders (3) and (4) and between the outer blade holder (4) and the anchoring structure (8), said plates being made of a sliding material.
