A safe guarding assembly for a grinding gun has a body, a rear protective cap and a front protective cap. The body has a casing. The casing has a front end, a shaft hole and a retaining ring. The shaft hole is formed through the casing. The retaining ring is formed on and protrudes from the front end of the casing around the shaft hole. The rear protective cap is mounted securely around the retaining ring of the casing and has a front end, an inner thread, a through hole and a mounting ring. The mounting ring is formed on and protrudes from the front end of the rear protective cap and has an external surface and an outer thread. The front protective cap is mounted detachably around the mounting ring of the rear protective cap and has an inner thread and a conical segment.