A tension applying apparatus includes a tension applying member applying a tensile force to a drive cable by being pressed against the drive cable, a biasing member generating a biasing force for pressing the tension applying member against the drive cable, a holding member including a guide portion which restricts a moving direction of the tension applying member and a housing member housing the tension applying member and the holding member. The holding member is configured to change the moving direction of the tension applying member which is guided by the guide portion in a state where the holding member including a rotation shaft is housed within the housing member. The housing member includes a holding structure holding the holding member at a position to which the holding member rotates in a direction where a pressing angle of the tension applying member relative to the drive cable becomes shallow.