A fabrication method of a painless transdermal micro needle array is proposed to realize its inexpensive and mass production. In order to avoid a risk by breakage of the needle when the needle is penetrated into the epidermis, the array is made with biodegradable polymer, for example, PLA. The proposed method has the following processes, (1) a mold dies having many micro through-holes is heated over the melting point of PLA, (2) the heated mold comes into contact with surface of the PLA plate, (3) the melted PLA is poured into the through-holes, and (4) the formed PLA plate is cooled to less than the melting point and removed from the dies. It is difficult to fabricate the array device because of the ratio of needle height to the diameter is large. So, heating temperature, time of heating the plate, moving stroke of dies and demolding temperature were examined and then fabrication of high precision circular cylindrical shaped needle array became possible.
