A head for brush cutter for cutting grass and herbaceous plants, of the type comprising: - a plurality of cutting elements of the blade type and each having a front cutting portion , defined by an elongated section , and a rear hooking portion , connectable to the head due to a slotted section ; - a support body , engageable with a drive shaft of a brush cutter to rotate around an axis of symmetry (Y) of the support body , having a central portion , connectable to the drive shaft, and a peripheral portion , having a substantially disc-shaped conformation extending from the central portion radially around it; - a plurality of pins , engageable by the plurality of cutting elements through the insertion of the slotted section of a respective cutting element on a corresponding pin , radially distributed on the peripheral portion ; each pin having at least one outer surface having a first side facing the central portion ; - a plurality of keys connected to the central portion of the support body ; each key being engageable in contact with a respective pin and movable, under the activation by an operator, from a first position, in which the key is in contact with the side of the pin to which the key is facing, to a second position, in which the key is spaced apart from the side generating a passage opening adapted to allow the engagement of the cutting element on the pin due to the insertion of the slotted section on the pin ; - a plurality of elastic means , active on the plurality of keys to counteract their movement and distributed so that a respective elastic means is active on each key , said plurality of elastic means being adapted to return the plurality of keys from the second position to the first position once the action induced by the operator has ceased; characterized in that each key, belonging to the plurality of keys , moves from the first position to the second position and vice versa according to a radial trajectory passing through the axis of symmetry (Y) of the support body . - a plurality of cutting elements of the blade type and each having a front cutting portion , defined by an elongated section , and a rear hooking portion , connectable to the head due to a slotted section ; - a support body , engageable with a drive shaft of a brush cutter to rotate around an axis of symmetry (Y) of the support body , having a central portion , connectable to the drive shaft, and a peripheral portion , having a substantially disc-shaped conformation extending from the central portion radially around it; - a plurality of pins , engageable by the plurality of cutting elements through the insertion of the slotted section of a respective cutting element on a corresponding pin , radially distributed on the peripheral portion ; each pin having at least one outer surface having a first side facing the central portion ; - a plurality of keys connected to the central portion of the support body ; each key being engageable in contact with a respective pin and movable, under the activation by an operator, from a first position, in which the key is in contact with the side of the pin to which the key is facing, to a second position, in which the key is spaced apart from the side generating a passage opening adapted to allow the engagement of the cutting element on the pin due to the insertion of the slotted section on the pin ; - a plurality of elastic means , active on the plurality of keys to counteract their movement and distributed so that a respective elastic means is active on each key , said plurality of elastic means being adapted to return the plurality of keys from the second position to the first position once the action induced by the operator has ceased; <EOS>