PROBLEM TO BE SOLVED: To provide a drug solution injector which surely prevents a needlepoint of a needle from unexpectedly sticking out from a cover member and chemical from unexpectedly flowing out through the needle.SOLUTION: The drug solution injector 1A includes the needle 5, an outer casing 2, a supporter 6A having a flow path whose tip end communicates with the inside of the needle 5 and rear anchor communicates with the inside of the outer casing 2, an operating mechanism for selecting a communicating state for communicating the inside of the needle 5 with the inside of the outer casing 2 through the flow path and a blocking state for blocking the communicating state by rotating the supporter 6A, and an exposure preventing means for preventing the needlepoint 51 from exposure, and the operating mechanism is constructed by at least one of the two members, the cover member 7A supported for moving between the first position for covering the needle 5 to the needlepoint 51 and the second position for exposing the needlepoint 51 and a cap 9 fixed to the outer casing 2 in a detachable manner and connected rotatably to the supporter 6A in the fixed state for covering the needle 5 to the needlepoint 51.【課題】針管の針先がカバー部材から不本意に突出するのを確実に防止することができるとともに、薬液が針管を介して不本意に流出するのを確実に防止することができる薬液注入器具を提供すること。【解決手段】薬液注入器具１Ａは、針管５と、外筒２と、先端が針管５内と連通し、基端が外筒２内と連通し得る流路を有する支持部材６Ａと、支持部材６Ａを回転操作して、針管５内と外筒２内とが流路を介して連通する連通状態と、連通状態を遮断する遮断状態とを選択する操作を行なう操作機構と、針先５１が露出するのを防止する露出防止手段とを備え、操作機構は、針管５を針先５１まで覆う第１の位置と、針先５１が露出する第２の位置とに変位可能に支持されたカバー部材７Ａと、外筒２に着脱自在に装着され、その装着状態で支持部材６Ａを回転可能に連結され、かつ、針管５を針先５１まで覆うキャップ９の２つの部材のうちの少なくとも一方で構成されている。【選択図】図１２
