PROBLEM TO BE SOLVED: To provide a drug injection device for preventing backflow of a discharged liquid drug. SOLUTION: A long insertion part 52 to be inserted into the body, a storage container having a mouth part connectable to the other end part of the insertion part at the tip, and storing a fluid drug, and the other insertion part. Between the pair of pressing plates, which has a base end on the end side and which is provided with a pair of pressing plates 54 displaceable in the direction toward and away from the storage container on both sides of the storage container, and between the pair of pressing plates and the storage container And a holder part having a pair of clamping pieces for clamping the side surface part of the storage part, and a drug channel part formed inside the insertion part, into which the fluid drug extruded from the storage container is guided, The fluidity that is provided with the medicine flow path portion and the medicine ejection hole 58 that communicates with the outside, and that displaces the pair of pressing plates in the direction close to the storage portion and is stored in the storage container via the pair of sandwiching pieces. A drug injection device 300 including a pressing plate separation restricting means for restricting separation of a pair of pressing plates when the drug is ejected from the drug ejection hole to the outside. [Selection diagram] Fig. 4【課題】吐出された流動性薬剤の逆流を防止する薬剤注入器具を提供する。【解決手段】体内に挿入される長尺状の挿入部５２と、挿入部の他方端部に接続可能な口部を先端に有し、流動性薬剤を貯留する貯留容器と、挿入部の他方端部側に基端部が設けられ、貯留容器に接近離間する方向へ変位可能な押圧板５４を、貯留容器を挟んだ両側に一対備える押圧手段と、一対の押圧板と貯留容器との間に配置され、かつ、貯留部の側面部を挟持する一対の挟持片を有するホルダー部と、挿入部の内部に形成され、貯留容器から押し出された流動性薬剤が導かれる薬剤流路部と、薬剤流路部及び外部を連通する薬剤吐出孔５８とを備えており、一対の押圧板を、貯留部に近接する方向に変位させ、一対の挟持片を介して貯留容器に貯留される流動性薬剤を薬剤吐出孔から外部に吐出させた際に、一対の押圧板同士の離間を規制する押圧板離間規制手段を備える薬剤注入器具３００。【選択図】図４
