A pharmaceutical preparation injecting instrument includes an outer needle and an inner needle. The outer needle has a straight tube shape having a distal side opening and a proximal side opening, and has a reference puncturing part on a distal side. The inner needle is configured to be removably inserted in the outer needle, and has a periphery puncturing part on a distal side. The inner needle is configured to allow the periphery puncturing part to appear from, or disappear into, the distal side opening in accordance with an advancing or withdrawing operation on the base side. When the inner needle is removed from the outer needle, the instrument is capable of injecting, from the distal side opening, a pharmaceutical preparation supplied from the proximal side opening. The outer needle guides the inner needle to project the periphery puncturing part to a side opposite the reference puncturing part.
