Provided are skin incision instrument to efficiently incise minimal portions and a method for incising skin with the skin incision instrument. The skin incision instrument according to the present invention comprises a holder, a needle, a needle drive unit, two or more skin expander sets, and a reader, wherein the skin expander sets comprise a first skin expander and a second skin expander the first skin expander and the second skin expander are capable of expanding skin at both sides of the linear incision portion away from the linear incision portion and expanding the linear incision portion in a direction to expand the linear incision portion and, minimal portions are efficiently incised by selecting a single skin expander set from two or more of the skin expander set based on the direction of the linear incision portion, such that an angle is adjusted to 45 degrees or more and 90 degrees or less wherein the angle is formed by the direction of the linear incision portion read by the reader and the direction to expand the skin by the single skin expander set.
