Abstract: A belt buckle includes a base frame for joining the ends of a belt which comprises a rectangular top recess on a top wall thereof, two parallel sliding grooves transversely disposed at two opposite sides by said rectangular top recess, two pairs of holes respectively made on two opposite ends of either sliding groove, the sliding grooves having a respective front end opened and a respective rear end closed, each hole receiving a spring and a steel ball supported on the spring, the steel ball in either hole partially projecting into either sliding groove; and an ornamental face plate mounted on the rectangular top recess on the base frame and having two guide rails respectively inserted into the sliding grooves on the base frame, the guide rails having a respective pair of recessed portions at the bottom into which the steel balls in the holes of the base frame engage respectively.