To provide a wing lock which keeps an increment in external width dimension comparatively small without lowering much the strength of a gate when the wing lock is mounted onto a truck.

A wing lock is provided with a handle 4 to be operated while being put into turning movement, and with a stopper 2 which is pivotally moved to the direction opposite to the direction of the pivotal movement of the handle 4 in such a way as to be approached to/parted from a wing plate 20a following the pivotal movement of the handle 4, in which, the stopper 2 is energized by the handle 4, the end part of the stopper 2 is approached to the the wing plate 20a so as to be locked onto an initial position checking the release of the wing plate, and it is parted from the wing plate because of the pivotal movement of the handle 4 to its one direction, and is also pivotally moved to the direction that it is approached to the wing plate, by means of pivotal movement directed to the other direction.