Provided are a ceramic wiring substrate; a multi-piece ceramic wiring substrate array for providing a plurality of the wiring substrates; and a method for reliably producing the wiring substrate array. The ceramic wiring substrate includes a substrate main body, which has a front surface, a back surface, side surfaces, a groove surface located on a side toward the front surface, and a fracture surface located on a side toward the back surface; and a notch which has a concave shape in plan view, and which is provided on at least one of the side surfaces so as to extend between the front surface and the back surface, wherein, in the side surface having the notch, the boundary between the groove surface and the fracture surface has curved portions on opposite sides of the notch, the curved portions being convex toward the front surface of the substrate main body in side view.