A lesion diagnosis apparatus and method to determine a regularity of a shape of a lesion are provided. The lesion diagnosis apparatus to determine a regularity of a shape of a lesion, includes a lesion area detecting unit configured to form a lesion area by selecting virtual points along a boundary of a lesion included in an image, and a lesion diagnosing unit configured to determine the regularity of the shape of the lesion by analyzing a correlation of the selected virtual points.