Writing instrument or applicator having resin molded parts

A writing instrument or an applicator, configured as a mechanical pencil including a rotational drive mechanism for rotationally driving a rotatable cam based on writing pressure that a writing lead receives and configured to transmit rotational motion of the rotatable cam to the writing lead,

• wherein the rotational drive mechanism includes a holder member configured to rotatably and axially movably support the rotatable cam and a sliding member that is fitted in the holder member and configured to axially push the rotatable cam forward,
• the rotational drive mechanism is also configured to rotate the rotatable cam by axially moving the rotatable cam based on writing pressure that the writing lead receives,
• on the holder member, a columnar piece that functions as an axially long guide protrusion is formed and on the sliding member, a guide portion that functions as a guide recess corresponding to the columnar piece is formed, so as to fit the sliding member slidably in the columnar piece, and
• a cushion spring configured to produce a bias force to axially push the rotatable cam forward is arranged making contact with the sliding member.