A miniature motor having a rotor comprising a commutator having locating projections formed on the commutator reference surface coming in contact with a rotor core, and a rotor core having thereon locating key holes for engaging with the locating projections; the commutator being fitted to the rotor core by engaging the locating projections with the locating key holes until the commutator reference surface comes in contact with the rotor core; in which each of the locating projections has a temporary insertion portion at the tip thereof, whose cross-section is smaller than the cross-section of the locating key hole, and a full insertion portion for engaging with the locating key hole; the full insertion portion has such a length that the commutator tongue of the commutator is located at a position higher than the height of the rotor windings in a state where the temporary insertion portion is inserted into the locating key hole.