An applicator A is configured to transfer an active ingredient into a body through skin by a puncture in the skin with microneedles 32. The applicator A includes a piston plate 20 that is provided with a protrusion part 33 and protrusion parts 20d 1 to 20d 4 on a lower surface side of a main body 20a of the piston plate. The microneedles 32 are provided on a surface of the protrusion part 33. The protrusion parts 20d 1 to 20d 4 are provided in a periphery of the protrusion part 33 while spaced apart from the protrusion part 33.
