Linear scar formation in the scalp after suturing an incision has been considered unavoidable. It was not known why scars formed even if the hair bulb was left intact. The authors developed a subcutaneous tissue-shaving method for radical treatment of bromidrosis and studied the process of hair regeneration by using thick-tissue specimens. They suggest that stem cells (lower) are located not only in the lower end of the telogen hair follicles but also in the sebaceous isthmus at the secretory opening of the sebaceous gland (upper stem cells). They found that linear scars can be prevented and existing linear scars can be surgically treated by using a relaxed suture on a scalp incision to avoid excessive pressure on the upper stem cells.