The present invention concerns a protection device (2; 102) for bush cutters comprising a guide rod (8), a head (10) provided with a rotatable cutting tool (12) that during rotation defines a substantially circular cutting plane (18), a motor suited to operate the cutting tool (12), wherein the protection device (2; 102) comprises a coupling (6; 106) suited to fix it to the bush cutter. The protection device (2; 102) is carried out as a guard (4; 104) with a substantially flat base surface that, when installed on the bush cutter, mainly extends along the axis of the rod (8) inclined by an angle (α) with respect to the cutting plane (18). Furthermore, the perimeter of the base surface describes, at least partially at the level of the radial portion and, in the axial direction (Y), at the level of the front perimeter portion of the cutting plane (18), an arc (β) that coincides with or slightly projects beyond the perimeter of the cutting plane (18), wherein the arc (β) is provided at least on part of its extension with a downward folded edge (16; 116) suited to cover the front perimeter portion of the cutting plane (18) in the axial direction (Y).