An intradermal injection needle (1) is an intradermal injection needle assembly to be used by piercing the intradermal injection needle into the skin of a living body. The intradermal injection needle (1) has a hollow needle (4) having a blade edge pierceable into the skin and a discharge port (41) of an administration product； and a hub (2) holding the hollow needle. The hollow needle (4) has an outer diameter of 0.15 to 0.20mm. The discharge port (41) has a length of 0.10 to 0.80mm in an axial direction of the hollow needle. When the intradermal injection needle (1) is pierced into the skin of the living body, the discharge port (41) thereof is entirely subcutaneously pierceable within a range of 0.20 to 1.00mm.
