Provided are a writing tool for mounting on a finger and a writing tool finger holder which is capable of deforming a part for mounting on a finger, of the writing tool, in a suitable shape for transportation, storage and carrying, the holder enabling the writing tool in a retained condition to be retracted and retained up to at least a site close to a second joint 15 of an index finger, the holder being capable of freely adjusting the writing tool at an preferred angle to an orientation function and a condition stabilizing function in a writing condition. The part for mounting on the finger is provided so as to be integral with a linking member; by means of building-in, folding, inserting and removing, and winding, the holder is made deformable to a carried condition when not in use; a necessary shortest dimension of the writing tool in the written condition is divided into at least two sections, i.e., an axis body 1 and a cap 2; and then, the axis body 1 and the cap 2 are overlapped with each other by means of folding or storing to thereby shorten the writing tool in a retained condition, and the writing tool in the written condition is reversibly movable in a predetermined range to thereby make an angle of the writing tool adjustable.