Awire electric discharge machine that is configured to perform machining by moving a wire electrode stretched between an upper wire guide and a lower wire guide relative to a table on which a workpiece is placed, the wire electric discharge machine comprising: a wire guide moving means configured to slant the wire electrode at a predetermined angle; the wire electric discharge machine characterized by further comprising: a contact detector disposed on the upper wire guide; a controller configured to calculate a taper angle (α) of a tapered section of a tapered workpiece mounted on the table, based on positions obtained through measurement, by the contact detector, of two points (P1, P2) at arbitrary heights on the tapered section; and wherein the controller is configured to calculate wire support positions of the upper wire guide and the lower wire guide, as corrected distances (u, v) of the upper wire guide and the lower wire guide from an upper surface of the table in the z-axis direction, that give a target taper angle (θ) and a target shape dimension, based on a position of any one of the two points (P1, P2) measured, the calculated taper angle (α), the upper surface position of the workpiece obtained through measurement by the contact detector, and a position at which the tapered section and the upper surface of the workpiece intersect when there is no machining error wherein the corrected distances (u,v) are calculated as: u = z 3 + a tan α tan θ + x 5 2 + y 5 2 − x 1 2 + y 1 2 + z 3 − z 1 tan α tan θ − z 3 v = a + b tan α tan θ − u where x1, y1, z1: coordinates of P1; z3: z-coordinate of P3; x5, y5; coordinates of P5; a: distance from the upper surface of the table at a wire support position of the lower wire guide during machining; b: distance from the upper surface of the table at a wire support position of the upper wire guide during machining. a contact detector disposed on the upper wire guide; a controller configured to calculate a taper angle (α) of a tapered section of a tapered workpiece mounted on the table, based on positions obtained through measurement, by the contact detector, of two points (P1, P2) at arbitrary heights on the tapered section; and wherein the controller is configured to calculate wire support positions of the upper wire guide and the lower wire guide, as corrected distances (u, v) of the upper wire guide and the lower wire guide from an upper surface of the table in the z-axis direction, that give a target taper angle (θ) and a target shape dimension, based on a position of any one of the two points (P1, P2) measured, the calculated taper angle (α), the upper surface position of the workpiece obtained through measurement by the contact detector, and a position at which the tapered section and the upper surface of the workpiece intersect when there is no machining error wherein the corrected distances (u,v) are calculated as: u = z 3 + a tan α tan θ + x 5 2 + y 5 2 − x 1 2 + y 1 2 + z 3 − z 1 tan α tan θ − z 3 v = a + b tan α tan θ − u where x1, y1, z1: coordinates of P1; z3: z-coordinate of P3; x5, y5; coordinates of P5; a: distance from the upper surface of the table at a wire support position of the lower wire guide during machining; b: distance from the upper surface of the table at a wire support position of the upper wire guide during machining. x1, y1, z1: coordinates of P1; z3: z-coordinate of P3; x5, y5; coordinates of P5; a: distance from the upper surface of the table at a wire support position of the lower wire guide during machining; b: distance from the upper surface of the table at a wire support position of the upper wire guide during machining.