The liquid administration tool (10) includes an inner structure (1) having a tubular body (2) and a double-ended needle (71), and a liquid is discharged from the double-ended needle (71) by moving in the distal direction A position (A) for covering the distal needle tip of the double-ended needle (71), a position (E) for retracting from the position (A) in the proximal direction and exposing the distal needle tip (6) which is movable between a closed state and a closed state (B), in an unused state in which a pressing operation has not yet been performed, is disengaged during a pressing operation, and in a used state after the pressing operation is completed And a cap (9) to be reattached. The cap (9) has a plurality of engagement pieces (93) for restricting movement of the operation member 5 toward the distal end in an unused state, a cover member (93) at the position (A) in an unused state and a used state And a distal end wall portion (911) covering the opening portion (621) of the distal end portion (6) from the distal end side.液体投与具(10)は、筒体(2)と両頭針(71)とを備える内側構造体(1)と、先端方向に向かって移動することにより、液体を両頭針(71)から吐出させる押圧操作を行なう操作部材(5)と、両頭針(71)の先端側針先を覆う位置(A)と、位置(A)から基端方向に退避して、先端側針先が露出する位置(B)との間を移動可能なカバー部材(6)と、押圧操作が未だ行なわれていない未使用状態では装着され、押圧操作中では離脱され、押圧操作が完了した後の使用済状態では再装着されるキャップ(9)とを備える。キャップ(9)は、未使用状態で操作部材5の先端方向への移動を規制する複数枚の係合片(93)と、未使用状態と使用済状態とで位置(A)にあるカバー部材(6)の開口部(621)を先端側から覆う先端壁部(911)とを有する。
