The invention discloses a fastener used for fastening to a target structure. The fastener comprises a head part with an upper surface and an opposite lower surface, a first rod stretching out from thelower surface and provided with a free end part departing from the head part, and an indication element installed on the head part and provided with at least a first wing, wherein the first wing comprises a first horizontal part extending towards the first side of the head part, and a first indication part connected to the first horizontal part and extending towards the free end part of the firstrod; and when the first rod is driven to enter the target structure and reaches a predetermined joint depth, the first indication part pushes the target structure and is separated from the fastener.