To provide a die for manufacturing a pinholder-shaped microneedle using injection molding, in particular a die allowing easy cleaning of clogged holes and to be maintained in good conditions with ease.

A plurality of cut portions are formed on an edge of a cuboid metallic flat board, and a casting mold having recesses for making a line of microneedles is made of a pair of such metallic flat boards. The die is fabricated by the required number of the casting molds for use as a die in injection molding, which can be disassembled and easily cleaned. The pinholder-shaped microneedle in a good form can be fabricated. As a result, the die for injection molding which is easy to clean clogged holes of the die and easily maintained in good conditions can be provided by combination of the metallic flat boards.