Fastening device for fixing a craniotomy operculum to a cranial vault, designed to be placed in a craniotomy crack, comprising: - at least one supporting tensioner; - first closing means (11, 13) operatively connected to the supporting tensioner; - second closing means designed to be fastened to the supporting tensioner for completing its closure; - at least one handle removably connected to the supporting tensioner and designed to handle the device to take it from its rest position to its operating fastening position, wherein the first closing means (11, 13) are connected to a distal end of the supporting tensioner and the second closing means are designed to be fastened to the supporting tensioner in a position near the distal end of the supporting tensioner, so that, when the device is in its operating fastening position, the first closing means (11, 13) are placed against the internal distal cranial surface interna and the second closing means are placed against the external cranial surface, the first closing means (11, 13) comprising at least two elongated elastic arms operatively connected to the lower end of the tensioner, each of the elongated elastic arms ending in two small elongated arms transversally placed with respect to the elongated elastic arms, wherein the two small transverse arms are shaped as a tapered slider, suitable to enable a wedging of the two small transverse arms and their following sliding in the epidural space above the dura mater and the cranial vault, generating only a minimum disconnection of the dura mater, reducing to a minimum the danger of bleeding, the small transverse arms having a contact surface with the dura mater with a substantially oval shape, and having rounded ends with a geometry designed to make them slide when inserting them into the epidural space, characterised in that the elongated elastic arms have an elliptical section. - at least one supporting tensioner; - first closing means (11, 13) operatively connected to the supporting tensioner; - second closing means designed to be fastened to the supporting tensioner for completing its closure; - at least one handle removably connected to the supporting tensioner and designed to handle the device to take it from its rest position to its operating fastening position, wherein the first closing means (11, 13) are connected to a distal end of the supporting tensioner and the second closing means are designed to be fastened to the supporting tensioner in a position near the distal end of the supporting tensioner, so that, when the device is in its operating fastening position, the first closing means (11, 13) are placed against the internal distal cranial surface interna and the second closing means are placed against the external cranial surface, the first closing means (11, 13) comprising at least two elongated elastic arms operatively connected to the lower end of the tensioner, each of the elongated elastic arms ending in two small elongated arms transversally placed with respect to the elongated elastic arms, wherein the two small transverse arms are shaped as a tapered slider, suitable to enable a wedging of the two small transverse arms and their following sliding in the epidural space above the dura mater and the cranial vault, generating only a minimum disconnection of the dura mater, reducing to a minimum the danger of bleeding, the small transverse arms having a contact surface with the dura mater with a substantially oval shape, and having rounded ends with a geometry designed to make them slide when inserting them into the epidural space, characterised in that the elongated elastic arms have an elliptical section.