A microneedle device system includes a microneedle device having a sheet-like microneedle having a sheet in which one surface is a skin contact surface and the other surface is a rear surface, and in which a plurality of microneedles are formed substantially along a surface of the sheet, and in which the microneedles in the skin piercing region are raised from the skin contact surface so as to be capable of piercing skin if the sheet is bent in a thickness direction, an adhesive layer that is disposed on the sheet-like microneedle, and a liner that is attached to the adhesive layer so as to be releasable therefrom, and an auxiliary tool having a bending portion which bends the microneedle device in the thickness direction, and on which the microneedle device is mounted so as to be movable along the bending portion.