A holding member comprising: (a) a sheet-like substrate portion having a first surface and a second surface; and (b) a plurality of storage portions each penetrating the first surface and the second surface of the substrate portion and each protruding in a direction of a side of the first surface and in a form of a cylinder where a chemical container part is to be stored, and each storage portion being configured to store a whole portion of one of a plurality of syringe pistons therein; wherein the storage portions each comprise: a first opening end portion forming a loading and unloading mouth for the syringe piston at a protruded tip of each of the storage portions; a bulging portion where an inner wall face of each of the storage portions on a side of the first opening end portion bulges continuously from the first opening end portion in a direction of an inside of the cylinder, thereby forming an opening widened toward the first opening end portion; a second opening end portion formed at a base end of each of the storage portions by the second surface of the substrate portion; and a tapered-off portion where the inner wall face of each of the storage portions on a side of the second opening end portion is formed in such a way as to narrow toward the second opening end portion, further comprising a plurality of supporting pillars each formed on a side of the first surface of the substrate portion in such a way as to protrude higher than each of the storage portions; and further comprising connection ribs outside the cylinder of each of the storage portions, the connection ribs each connecting adjacent storage portions in a plurality of the storage portions, characterised in that the connection ribs are each formed at a position lower than a height from the first surface of the substrate portion to the bulging portion of each of the storage portions. (a) a sheet-like substrate portion having a first surface and a second surface; and (b) a plurality of storage portions each penetrating the first surface and the second surface of the substrate portion and each protruding in a direction of a side of the first surface and in a form of a cylinder where a chemical container part is to be stored, and each storage portion being configured to store a whole portion of one of a plurality of syringe pistons therein; wherein the storage portions each comprise: a first opening end portion forming a loading and unloading mouth for the syringe piston at a protruded tip of each of the storage portions; a bulging portion where an inner wall face of each of the storage portions on a side of the first opening end portion bulges continuously from the first opening end portion in a direction of an inside of the cylinder, thereby forming an opening widened toward the first opening end portion; a second opening end portion formed at a base end of each of the storage portions by the second surface of the substrate portion; and a tapered-off portion where the inner wall face of each of the storage portions on a side of the second opening end portion is formed in such a way as to narrow toward the second opening end portion, a first opening end portion forming a loading and unloading mouth for the syringe piston at a protruded tip of each of the storage portions; a bulging portion where an inner wall face of each of the storage portions on a side of the first opening end portion bulges continuously from the first opening end portion in a direction of an inside of the cylinder, thereby forming an opening widened toward the first opening end portion; a second opening end portion formed at a base end of each of the storage portions by the second surface of the substrate portion; and a tapered-off portion where the inner wall face of each of the storage portions on a side of the second opening end portion is formed in such a way as to narrow toward the second opening end portion,