An injection needle assembly includes a hollow needle having a needle tip for puncturing skin； a holding portion that holds the hollow needle； a fitting portion having a tapered inner surface configured such that a drug discharge portion of a drug container is insertable into the fitting portion, the fitting portion including a screw portion on its outer peripheral face； and a restriction portion configured to restrict a distance by which the drug discharge portion is pushed into the fitting portion by contacting a locking mechanism of the drug container when the drug discharge portion is inserted into the fitting portion and a screw portion of the locking mechanism is threaded into the screw portion of the fitting portion.
