A driving force interrupting mechanism includes input and output members. A coupling sleeve is to be movable on the input and output members along a rotational axis. A fork is swingable around a swing shaft to move the coupling sleeve between a connecting position and a disconnecting position. The coupling sleeve is positioned on both of the input and output members in the connecting position. The coupling sleeve is positioned on either the input member or the output member in the disconnecting position. An operating member is integrally rotatable with the swing shaft. A spring is provided on the swing shaft between the operating member and the fork relatively rotatably with respect to the swing shaft. A motion of one of the operating member and the fork follows a motion of another of the operating member and the fork via an elastic force of the spring.