To provide a pierced earring hole forming device including a malfunction preventing mechanism and a stable earlobe presser member.

A flexible stopper member of long plate shape with one tip fixed to a receiving side case 1 is located to be slidable relative to a body case 2 on the bottom face side of the body case 2, and the other tip is formed with a hook part lockable to a through hole formed in the bottom face of the body case. The bottom face side of the stopper member is mounted with a push piece 10 that can be pushed in the longitudinal direction of the stopper member, and the push piece 10 is pushed in to allow the hook member to escape from the through hole and to move the receiving side case 1 horizontally in a direction to separate from the body case 2. A second return spring 11 is provided for returning the receiving side case 1 toward the body case 2 when pressing force to the push piece 10 is released.