Circuit width thinning defect prevention device and method of preventing circuit width thinning defect

The present invention relates to a circuit width thinning defect prevention device and a method of preventing a circuit width thinning defect, and can prevent a circuit width thinning defect, that is, a reduction in circuit width due to excessive etching on a specific portion by including a storage means for storing dam design information classified according to the type of a weak portion; an analysis means for analyzing first design information to deduce the type and position of the weak portion; a matching means for extracting the dam design information corresponding to the type of the weak portion from the dam design information stored in the storage means; and a change means for changing the first design information to add a dam according to the dam design information extracted by the matching means to the position of the weak portion deduced by the analysis means.