To smoothly perform embedding work without damaging the tip of a bolt by forming a rotary inserting short body part rotatably fitted to a through inserting hole in a socket adapter body, and arranging a nonstriking contact part on the upper end of the socket adapter body.

In this socket adapter, a through part to a tip through-hole 2 of a hammer drill 1 is formed as a short body part 3 formed in the length for generating a space 6 for not allowing a hammer drill striking part 5 to abut on an upper end part 7 together with a collar part 4. Then, only rotation of the hammer drill is transmitted to a socket K. A weak stroke can also be imparted to the socket K by arranging a projecting part. Thus, embedding work to concrete can be extremely smoothly performed without damaging the tip of a bolt.