An optical fiber splicing tool of the invention include: an optical fiber splicing unit that includes: an optical fiber grasper that grasps a first optical fiber at a mechanical splice; and a guide target that is slidable along a guide provided at a connecting jig that fixes a second optical fiber to be butt-jointed to the first optical fiber; and a connecting jig that includes: a guide that guides the optical fiber splicing unit; and an optical fiber fixer that fixes the second optical fiber. The optical fiber splicing unit provides a first flexure width between one end side of the mechanical splice and the optical fiber grasper, and a second flexure width shorter than the first flexure width is ensured between the other end side of the mechanical splice and the optical fiber fixer when butt-jointing is carried out.