The invention relates to a transdermal microneedle array patch for measuring a concentration of a hypodermal target molecule. The transdermal microneedle array patch includes a substrate, a microneedle unit, a signal processing unit and a power supply unit. The microneedle unit at least comprises a first microneedle set used as a working electrode and a second microneedle set used as a reference electrode, the first and second microneedle sets arranging on the substrate. Each microneedle set comprises at least a microneedle. The first microneedle set comprises at least a sheet having a through hole on which a barbule forms at the edge. One of the sheet provides the through hole from which the barbules at the edge of the other sheets go through, and the barbules are disposed separately.