Malignant melanoma is a neoplasm of melanocytes or a neoplasm of the cells that develop from melanocytes. It may develop in or near a previously existing precursor lesion. Clinically, asymmetrical and irregular borders with the diameter greater than 6 mm are typical at first diagnosis. A 56-year-old woman presented with asymptomatic solitary violaceous plaque on left temporal area. The lesion was blurred toward the lateral side with a crust in the center. It occurred 4 months ago, and the size became rapidly larger after laser therapy at a private hospital. And the patient had no family history of melanoma. Histopathologic examination of the lesion shows nests of melanocytes with variable size and shape, and atypical mitoses. S-100 protein, Melan A, HMB45 presented positive stains. She was diagnosed with malignant melanoma by skin biopsy and transferred to plastic surgery for excision. Melanoma, especially in extremity, may occur after trauma. Few cases of melanoma after laser therapy have been reported and it is still unknown whether melanoma can be induced by lasers. In our case, the clinical features of the patient differed from the typical findings of malignant melanoma. Laser treatment is thought to be associated with a unique clinical feature in one point, which is suddenly increased after laser treatment. So, a careful examination of all pigmented lesions is needed to prevent increase the risk of delayed melanoma diagnosis.