A writing instrument (1) is provided with an erasing member (2) mounted to the rear end section of the writing instrument body (3) or to the front end section of a cap (4). The end section has a fitting section (14) which is disposed on the center axis and a connection section (15) which connects the end section and the fitting section (14). The erasing member (2) has a fitting hole (2c) which receives both the fitting section (14) and the connection section (15). When the erasing member (2) is mounted in position, a gap space (17) is formed around the connection section (15).