A mechanical pencil 1 has a first cam surface 140a, a second cam surface 140b, a first fixed cam surface 141a that cooperates with the first cam surface to cause a rotating element to rotate, and a second fixed cam surface that cooperates with the second cam surface to cause a rotating element to rotate. The first cam surface is provided with first cam teeth 140aa, the second cam surface is provided with second cam teeth 140ba, the first fixed cam surface is provided with first fixed cam teeth 141aa that cooperate with the first cam teeth, and the second fixed cam surface is provided with second fixed cam teeth 142aa that cooperate with the second cam teeth. The first cam teeth are configured such that in each first cam tooth, the relationship 0<Y<X is achieved, where, with respect to a perpendicular line drawn from the apex, X is the length of the base on the rear side with respect to the rotating direction of the rotating element 140, and Y is the length of the base on the front side with respect to the rotating direction of the rotating element.

A mechanical pencil 1 has a first cam surface 140a, a second cam surface 140b, a first fixed cam surface 141a that cooperates with the first cam surface to cause a rotating element to rotate, and a second fixed cam surface that cooperates with the second cam surface to cause a rotating element to rotate. The first cam surface is provided with first cam teeth 140aa, the second cam surface is provided with second cam teeth 140ba, the first fixed cam surface is provided with first fixed cam teeth 141aa that cooperate with the first cam teeth, and the second fixed cam surface is provided with second fixed cam teeth 142aa that cooperate with the second cam teeth. The first cam teeth are configured such that in each first cam tooth, the relationship 0<Y<X is achieved, where, with respect to a perpendicular line drawn from the apex, X is the length of the base on the rear side with respect to the rotating direction of the rotating element 140, and Y is the length of the base on the front side with respect to the rotating direction of the rotating element.