Various implementations relate to a guide device for spinal surgery, comprising: two guide sleeves extending between a proximal end and a distal end for guiding a surgical intervention on a vertebra of a patient; a plurality of support elements, wherein each support element defines a contact area specifically configured for abutting against a portion of a virtual surface reproducing the vertebra of the patient, in a coupling configuration; and at least one junction element joining the two guide sleeves together. Each guide sleeve comprises a respective auxiliary sleeve extending between a proximal end and a distal end, and the proximal end of the auxiliary sleeve is located in proximity to the proximal end of the respective guide sleeve.