To provide a marking tool such that the circumference of a ring member can be easily and equally divided into a desired number of divisions and the equally divided places can be accurately and efficiently marked to make the marking operation higher in precision and efficient.

There is provided a marking tool 1 used to equally divide circumferences of ring members 24, 34 into desired numbers of divisions, the marking tool including a first belt-like spring member 2 which has a plurality of through holes 2a formed at predetermined intervals α along a beltlike length direction, and is easy to curve, a second belt-like spring member 3 which has a plurality of through holes 3a formed at predetermined intervals β (β=2α) along a beltlike length direction, and is easy to curve, a linear long member 4 which can be inserted into the through holes 2b of the first belt-like spring member 2 and the through holes 3b of the first belt-like spring member 3, and a linear short member 5 which can be inserted into the through holes 2a of the first belt-like spring member 2 and the through holes 3a of the first belt-like spring member 3.