The present invention discloses a prosthetic implant and an insertion instrument for inserting the prosthetic implant between adjacent vertebrae. The prosthetic implant in accordance with the present invention includes a housing for being packed with bone chips, an inserting hole formed at a first end of the housing, through which an insertion instrument can be inserted, and a connection recess formed on inner surface of the housing around the inserting hole, on which the insertion instrument is stably placed. The insertion instrument in accordance with the present invention includes a connection member having a connection chip at a first end, a rotating means for rotating and returning the connection member at a predetermined angle. In accordance with the present invention, the insertion instrument can be separated from the prosthetic implant by rotation of only one time after the prosthetic implanted is completely inserted, so that the operation process of implanting the prosthetic implant is easy and safe. Further, the prosthetic implant in accordance with the present invention safely and stably fixed between the adjacent vertebrae because projections are formed at the upper end and lower end of the prosthetic implant respectively.