An inserter includes a housing, a plunger holding an indwelling member, a lifter contained in the housing in the state where the lifter is axially movable relative to the plunger, a needle holder contained in the housing and having a projection that can be latched by the plunger and the lifter, an insertion needle held by the needle holder and inserted in a cannula, and a spring provided between the plunger and the lifter and applying a biasing force in the direction of biasing the plunger and the lifter away from each other. The projection of the needle holder is latched by the plunger before the indwelling member reaches the body surface of the user, and latched by the lifter after the indwelling member reaches the body surface of the user.
