A skin incision device has a casing having a bottom surface with a slot formed therein, a cover positioned on the casing and slidable in a direction toward the bottom surface, a blade positioned in the casing adjacent the slot, an actuator cooperatively positioned between the cover and an interior of the casing, and a carriage element. The actuator engages the blade by its horizontal displacement triggered by the slidable movement of the cover toward the bottom surface of the casing. The carriage element guides the movement of the blade between a pre-actuated position and a post-actuated position. The blade moves outwardly through the slot, cuts with a horizontal movement, and returns inwardly through the slot.