An applicator 10 for applying a microneedle to a skin includes a tubular housing 11, a piston 20 which transmits a biasing force of a spring 40 to the microneedle, fixation means (a claw receiving portion 16 and claw portions 22a) for fixing the piston 20 against the biasing force of the spring 40 in the housing 11, and a cap 30 provided near a first end of the housing 11. A projecting portion 31 for releasing the piston 20 fixed by the fixation means is provided at a surface of the cap 30 facing the piston 20. The cap 30 is provided to be freely movable in an extending direction of the housing 11 such that the projecting portion 31 can contact the fixation means when the piston 20 is fixed by the fixation means.