A black key for a keyboard instrument, in which a black key cover incorporating a weight can be manufactured at low costs, and the black key cover can be firmly mounted on a key body, in a state stably holding the weight in a black key cover body. A swingable key body extends in a front-rear direction. A black key cover body has a hollow shape opening downward, and is mounted on a front portion of the upper surface of the key body in a manner covering the front portion. A weight is received within the black key cover body. The black key cover body has at least one of lower walls protruding inward from lower portions of left and right side walls, for holding the weight from below. The lower surfaces of the lower walls are bonded to the key body.