Tool changer device, comprising a stationary head, wherein is provided a cam exchanger mechanism, that transforms uniform rotary input movement, provided by a gear motor unit, into an ordered series of intermittent linear and rotary movements of an output shaft, having an axis (X-X) and on which is mounted an arm carrying at least one tool gripper, and wherein said gripper comprises an outer jaw (11.1) and an inner jaw (11.2), with reference to said axis (X-X), wherein - said jaws (11.1, 11.2) can move with respect to one another with a straight-line movement, by means of respective rods (11.11, 11.21), guided (11.12, 11.22) in a box-type body (10.1) of said arm and sliding along a plane at right angles to said axis (X-X), - each of said rods (11.11, 11.12) has a respective free axial end (11.13, 11.23), near said axis (X-X), wherein there is provided a respective slot-type through hole (11.14, 11.24), the axes of which lie along a plane at right angles to said axis (X-X), the long axis being parallel to the direction of sliding of the respective rod, - on opposing sides of their lateral surfaces, said rods (11.11, 11.21) have a respective rack (11.15, 11.25), which extends along a plane at right angles to said axis (X-X) and is engaged with a corresponding pinion with an axis (Y-Y) parallel to said axis (X-X) of said shaft, - an elastic means directly acts on one (11.21) of said rods (11.11, 11.21) and causes the corresponding jaw (11.2) to close, approaching the other jaw (11.1), which in turn is indirectly acted on by said same elastic means, by means of its rod (11.11), the relative rack (11.15), said pinion and the other rack (11.25), and caused to close and approach the afore-mentioned jaw (11.2), wherein - corresponding with each of said slot-type holes (11.14, 11.24), there is provided a respective movable shutter, which projects partly on the outside of said box-type body (10.1), through a corresponding hole near said head, - an elastic means (14.3) normally maintains said shutter partially extended beyond the box-type body (10.1) and in contact with an opposing surface of said and said shutter, in this condition, through the corresponding slot-type hole (11.14, 11.24) without interference, wherein each rod (11.11, 11.21), around the respective slot-type hole (11.14, 11.24), has a surface portion (11.110, 11.210) that is conically countersunk towards a corresponding part (14.1) of the respective shutter and, correspondingly, said corresponding part (14.1) of the respective shutter has a portion (14.10) that is near said slot-type hole, conically countersunk and of a shape that is substantially complementary to that of said conically countersunk surface portion (11.110, 11.210) of said rod (11.11, 11.21), and wherein, in a condition wherein said shutter is no longer in contact with said opposing surface of the head, said elastic means (14.3) acts on said corresponding part (14.1) of the shutter in contact with the respective rod (11.1, 11.21), and said portion (14.10) of the shutter engages with said surface portion (11.110, 11.210) of the respective rod (11.11, 11.21), thereby creating solid interference between the parts, and preventing the movement of the rod and the corresponding jaw (11.1, 11.2). - said jaws (11.1, 11.2) can move with respect to one another with a straight-line movement, by means of respective rods (11.11, 11.21), guided (11.12, 11.22) in a box-type body (10.1) of said arm and sliding along a plane at right angles to said axis (X-X), - each of said rods (11.11, 11.12) has a respective free axial end (11.13, 11.23), near said axis (X-X), wherein there is provided a respective slot-type through hole (11.14, 11.24), the axes of which lie along a plane at right angles to said axis (X-X), the long axis being parallel to the direction of sliding of the respective rod, - on opposing sides of their lateral surfaces, said rods (11.11, 11.21) have a respective rack (11.15, 11.25), which extends along a plane at right angles to said axis (X-X) and is engaged with a corresponding pinion with an axis (Y-Y) parallel to said axis (X-X) of said shaft, - an elastic means directly acts on one (11.21) of said rods (11.11, 11.21) and causes the corresponding jaw (11.2) to close, approaching the other jaw (11.1), which in turn is indirectly acted on by said same elastic means, by means of its rod (11.11), the relative rack (11.15), said pinion and the other rack (11.25), and caused to close and approach the afore-mentioned jaw (11.2), wherein - corresponding with each of said slot-type holes (11.14, 11.24), there is provided a respective movable shutter, which projects partly on the outside of said box-type body (10.1), through a corresponding hole near said head, - an elastic means (14.3) normally maintains said shutter partially extended beyond the box-type body (10.1) and in contact with an opposing surface of said and said shutter, in this condition, through the corresponding slot-type hole (11.14, 11.24) without interference,