A buckle assembly includes female and male buckle plates. The female buckle plate is formed with an insertion slot defined by a slot-defining wall having first and second wall faces, and has first and second corners. The first and second corners oppose each other, and are different in height with respect to a reference plane. The male buckle plate has a bent end portion that has upper and lower segments and a middle segment cooperating with the upper and lower segments to define upper and lower corners. The bent end portion is pivotable to the first corner by abutting the upper corner against the first corner, such that the bent end portion is rotatable relative to the first corner.