A disposable circumcision anastomat comprises an internal ring (2) and an external ring (1) having an opening (10). The internal ring (2) substantially matches an external ring (1). The external ring (1) includes a sidewall (100). The sidewall (100) is provided with a retainer (7) for holding a gasket. The retainer (7) is an annular ring (71) extended inwardly from the sidewall (100) of the external ring. The annular ring (71) is equipped with an opening (710), corresponding to opening (10) on the external ring. The width (K1) of the annular ring is less than the width (K 2) of the blade. The apparatus is safe, reliable, and able to reduce pain experienced by patients after surgery.