A device for transcutaneous biopsy includes a casing consisting of a first half shell and a second half shell that are fixable to one another. Inside the casing there is defined a chamber into which slides a slide element to which a first cannula and a second cannula are connected. The second cannula is inserted inside the first cannula, both of them having a common longitudinal axis. The first cannula is provided with a locking element. The locking element, which is suitable for interacting with the second cannula, is provided with a pair of notches interacting with a pair of lamina elements with which the second cannula is provided.