A buckle device includes a body, a fastening element and a latch assembly. A first strap is secured to the body. The fastening element includes a rod formed thereon. The fastening element is mounted on the body so that it can be pivoted between a first position for allowing winding of a second strap around the rod and a second position for tensing up the second strap by means of the rod. The latch assembly can retain the fastening element in the second position. The body includes two side plates. The fastening element includes two side plates between which the rod is formed. A shaft is used to mount the fastening element on the body. The side plates of the body each define a hole for receiving the shaft. The side plates of the fastening element each define a hole for receiving the shaft. The latch assembly includes a latch mounted on the fastening element. Each of the side plates of the body includes a hook formed thereon for engagement with the latch when the fastening element is in the second position relative to the body. The latch includes two fins. Each of the side plates of the fastening element defines a slot for receiving one of the fins of the latch. An elastic element is connected between the fastening element and the latch for forcing the latch into engagement with the hooks when the fastening element reaches the second position relative to the body.