A drilling mask for implanting a transpedicular screw to a spine section, said spine section having a vertebral body with a spinous process, a vertebral lamina and a articular process with a relative pedicle, said drilling mask comprising: - a guide body having a distal surface and a proximal surface, opposite to said distal surface and suitable for facing towards said spine section, - a reference element obtained on said proximal surface and arranged to contact said spinous process, - a guide channel having an inlet in said distal surface and arranged to work as drilling guide for drilling said pedicle and implanting said transpedicular screw; - a plurality of support elements (22, 23) made on said proximal surface, associated with said reference element and arranged to contact side parts of said spine section, wherein said guide body comprises: - at least one reference portion, comprising said reference element, configured to be put at said spinous process, and - a lateral guide portion (10b, 10c), cooperating with said reference portion, and comprising said guide channel for drilling said pedicle, where said reference portion and said lateral guide portion (10b, 10c) are mutually coupled to each other through releasable mutual engagement means, in such a way that said guide body can, when mounted to said spire section, move from a use configuration, where said reference portion and said lateral guide portion (10b, 10c) are connected to each other for introducing said transpedicular screw, to an extraction configuration, where said reference portion and said lateral guide portion (10b, 10c) are disassembled from each other characterised in that said reference portion and said lateral guide portion (10b, 10c) are disassembled from each other for removal of said lateral guide portion (10b, 10c) from said reference portion in a direction substantially parallel with respect to an axis of said guide channel and for removal of said reference portion from said spine section in a direction substantially parallel to said spinous process, and in that said reference element is an element having a groove arranged to engage bridging said spinous process. - a guide body having a distal surface and a proximal surface, opposite to said distal surface and suitable for facing towards said spine section, - a reference element obtained on said proximal surface and arranged to contact said spinous process, - a guide channel having an inlet in said distal surface and arranged to work as drilling guide for drilling said pedicle and implanting said transpedicular screw; - a plurality of support elements (22, 23) made on said proximal surface, associated with said reference element and arranged to contact side parts of said spine section, - at least one reference portion, comprising said reference element, configured to be put at said spinous process, and - a lateral guide portion (10b, 10c), cooperating with said reference portion, and comprising said guide channel for drilling said pedicle, where said reference portion and said lateral guide portion (10b, 10c) are mutually coupled to each other through releasable mutual engagement means, in such a way that said guide body can, when mounted to said spire section, move from a use configuration, where said reference portion and said lateral guide portion (10b, 10c) are connected to each other for introducing said transpedicular screw, to an extraction configuration, where said reference portion and said lateral guide portion (10b, 10c) are disassembled from each other