A method for identification of a crack on the surface of the material by means of direct-current electrical potential difference method of multiple-point measurement type was proposed and related experiments were carried out to verify the proposed method. The geometry of the crack was given by the two-dimensional location of the crack center, the surface and inward angles of the crack, the length and depth of the crack. The experiments were carried out for metal plates with various surface cracks made by electric discharge machining. When most of the area of potential disturbance by a crack was included in the measurement area, the geometry of the crack was successfully identified by the proposed method based on the potential differences measured at multiple locations around the crack.