A chuck unit (4) for grasping a writing lead (10) and a rotor (6) arranged to be movable in a direction of rotation and an axial direction within a body cylinder (1) are provided. First and second cam faces (6a) and (6b) are respectively formed at one end face and another end face of the rotor in the axial direction, and first and second fixed cam faces (13a) and (17a) are arranged on the body cylinder side to face the first and second cam faces respectively. The first cam face in the rotor is brought into abutment with and meshed with the first fixed cam face by retreat operation of the chuck unit under writing pressure, and the second cam face in the rotor is brought into abutment with and meshed with the second fixed cam face by releasing the writing pressure, so that the rotor rotates, whereby the writing lead also rotates.