Abstract: A mechanical pencil has a front sleeve, a cap rotatably and detachably mounted at the rear end of the front sleeve, and a lead advancing mechanism contained in the front sleeve. Rotation of the cap actuates the lead advancing mechanism to advance a lead. The mechanical pencil prevents breakage of lead and has low manufacturing costs. A rotation cam mechanism is disposed behind the lead advancing mechanism for advancing lead. The rotation cam mechanism has a rotation cam for rotating in accordance with rotation of a cap and a cam sleeve biased to engaged the rotation cam. An inside diameter of the front end of the cam sleeve is larger than an outside diameter of the rear end of the lead advancing mechanism so that the rear end of the lead advancing mechanism is inserted into the front end of the cam sleeve with a clearance in the radial direction. An inside diameter of the rear end of the lead advancing mechanism is larger than the outside diameter of a lead to establish a clearance there also.