A fixator of a cranial flap to a skull, the fixator comprising a rigid rod, a lower disk placed at a distal extremity of said rigid rod, an upper disk mounted so as to be mobile along said rigid rod and a grip connected to the proximal extremity of said rigid rod enabling said upper disk to be made to slide towards said lower disk, said distal extremity of said rigid rod being provided with a ball-joint element and said lower disk comprising a recess for receiving said ball-joint element; said lower disk and said upper disk have convex shapes and are made out of a material enabling them to get deformed and adapt to shapes of the skull and the cranial flap, the lower and upper disks are placed flat against and secured to the internal and external surfaces of the skull and of the cranial flap.