A shading area having a transmissivity in the range of 0 to 2% is formed at the center of a clear defect in a wiring pattern of a half tone mask. Semitransparent areas having a transmissivity in the range of 10 to 25% are formed, adjacently to shading area, in areas extending from the inside of the edge of an imaginary pattern having no defect to the outside of the edge. In this way, in the correction of the defect in the half tone mask, the working accuracy tolerable margin of the correction portion of the defect can be made large.