To provide a wall structure capable of increasing strength and rigidity of a bearing wall further without increasing thicknesses of a structural wall and a reinforcing wall.

This wall structure of the building includes a plurality of horizontal plates 13 constituting the structural wall 5, a plurality of vertical plates 18 constituting the reinforcing wall 6 on a rear surface side of the structural wall 5, a wall fastener 1 for attaching both of end parts of the structural wall 5 and the reinforcing wall 6 to mutually opposing faces of a pair of columns 4, a lateral slippage prevention implement 35 provided on the structural wall 5 to prevent respective stacked horizontal plates 13 from slipping relatively in the longitudinal direction, a plurality of narrow mouth grooves formed on surfaces of the horizontal plate 13 and the vertical plate 18 and having width of groove on an opening side set to be smaller than width of groove on an innermost side, and a painted wall constructed by painting a wall material such as soil or the like on the surfaces of the structural wall 5 and the reinforcing wall 6 to fill the inside of the narrow mouth groove with the wall material.