Wire electric discharge machining apparatus

A wire electric discharge machining apparatus having a wire electrode vertically aligned between an upper guide unit and a lower guide unit, comprising:

• an arm, having a lower end provided with the upper guide unit;
• an axis drive portion configured to vertically move the arm, and the axis drive portion being made of cast iron;
• a lower support, made of a material that has a smaller coefficient of linear expansion than that of cast iron, and the lower guide unit being fixed to one end of the lower support;
• and
• an adjustment block, fixed to the arm and made of a material that has a smaller coefficient of linear expansion than that of cast iron,
• wherein an upper surface of the adjustment block is fixed to a bottom surface of the axis drive portion to connect the arm and the axis drive portion,
• wherein the adjustment block is fixed at a position where a displacement of the upper guide unit caused by expansion and contraction of the axis drive portion is suppressed by a bimetal effect occurring on a fastening surface of the axis drive portion and the adjustment block.