The anti-theft fastener has a shearing head, a shaft and a fastening element. The shearing head has at least one shearing tab. The shaft is threaded and connected the shearing head. The fastening element is mounted around the shearing head and has an outer surface having a countersink and at least one shearing recess. The countersink is formed in the outer surface around the connecting hole. The at least one shearing recess is formed in countersink, and corresponds to the at least one shearing tab, and each shearing recess has at least one shearing surface, whereby the at least one shearing tab is broken off by the shearing surface of the fastening element.