A method for manufacturing a ball for ball games that has a ball body and a spherical shell-shaped outer layer having a plurality of leather panels and disposed on an outside of the ball body, the method comprising: a leather panel formation step of obtaining each of the leather panels by forming, in a member for leather panel, a main body and an extending portion that is thinner than the main body and reinforced with a reinforcing member configured with one or more fabrics, the main body and the extending portion each having a leather material and a rear surface member secured to a rear surface of the leather material; an application step of applying an adhesive to an outer surface of each of the extending portions; a joining step of bringing the outer surfaces of the extending portions of two leather panels to which the adhesive is applied into contact with each other; a stitching step of stitching together, with a stitching thread, the extending portions of the leather panels, the outer surfaces of which have come into contact with each other; and an insertion step of inserting the ball body into a spherical shell body that is obtained by repeating the joining step and the stitching step, the spherical shell body being obtained by turning over a spherical shell body in which the reinforcing members are located on a front side and the extending portions are folded to a front side, to obtain a ball, wherein the leather panel formation step includes: a step of attaching a rear surface member and the reinforcing member to a rear side of a leather material; and an extending portion formation step of forming the main body and the extending portion in each of the leather panels by denting an outer circumferential portion of the rear surface member that is cut into the shape of the leather panels, whereby obtaining the extending portion that is not yet folded and extends laterally and straight from the main body in the shape of a flange, so that the rear surface member is press-fitted between fibers of the reinforcing member. a leather panel formation step of obtaining each of the leather panels by forming, in a member for leather panel, a main body and an extending portion that is thinner than the main body and reinforced with a reinforcing member configured with one or more fabrics, the main body and the extending portion each having a leather material and a rear surface member secured to a rear surface of the leather material; an application step of applying an adhesive to an outer surface of each of the extending portions; a joining step of bringing the outer surfaces of the extending portions of two leather panels to which the adhesive is applied into contact with each other; a stitching step of stitching together, with a stitching thread, the extending portions of the leather panels, the outer surfaces of which have come into contact with each other; and an insertion step of inserting the ball body into a spherical shell body that is obtained by repeating the joining step and the stitching step, the spherical shell body being obtained by turning over a spherical shell body in which the reinforcing members are located on a front side and the extending portions are folded to a front side, to obtain a ball, wherein the leather panel formation step includes: a step of attaching a rear surface member and the reinforcing member to a rear side of a leather material; and an extending portion formation step of forming the main body and the extending portion in each of the leather panels by denting an outer circumferential portion of the rear surface member that is cut into the shape of the leather panels, whereby obtaining the extending portion that is not yet folded and extends laterally and straight from the main body in the shape of a flange, so that the rear surface member is press-fitted between fibers of the reinforcing member. a step of attaching a rear surface member and the reinforcing member to a rear side of a leather material; and an extending portion formation step of forming the main body and the extending portion in each of the leather panels by denting an outer circumferential portion of the rear surface member that is cut into the shape of the leather panels, whereby obtaining the extending portion that is not yet folded and extends laterally and straight from the main body in the shape of a flange, so that the rear surface member is press-fitted between fibers of the reinforcing member.