To provide an intrauterine injection instrument which puts a reduced load on livestock, particularly a pig, and is easy to use.SOLUTION: In an intrauterine injection instrument 1 for livestock with an outer catheter 11 and an inner catheter 12, a winding spring 13 is bonded to the inner surface 11p of the outer catheter 11, and the inner catheter 12 is inserted to the inside of the winding spring 13 while the inner catheter 12 is movable in an extension direction (X-axis direction) of the winding spring 13. Since the outer diameter of the outer catheter 11 is reduced by the configuration, it is possible to reduce the load on livestock such as a pig to which a fertilized egg or the like is to be transplanted.SELECTED DRAWING: Figure 2【課題】家畜、特に豚への負担が小さく容易に使用することができる子宮内注入器具を提供すること。 【解決手段】外側カテーテル１１と、内側カテーテル１２と、を備えた家畜の子宮内注入用器具１において、巻きバネ１３が、外側カテーテル１１の内側面１１Ｐに接着されており、内側カテーテル１２が、巻きバネ１３の伸長方向（Ｘ軸方向）に移動可能な状態で、巻きバネ１３の内側に挿入されている構成により、外側カテーテル１１の外径が細くなるから、受精卵等を移植される豚などの家畜への負担を小さくすることができる。【選択図】図２
