An adjustable buckle includes a base including a top column; a hollow rectangular sliding plate slidably put on the column and including inclined front and rear ends each falling into a dip between two of a series of ratchet teeth of either strap, two inclined sides, and a resilient assembly secured on the sliding plate; and a cover including two parallel side walls, front and rear struts each with the strap partially wrapped around, and two latches each on the side wall. Pressing the latches will lift the sliding plate with the resilient assembly being compressed, disengage the front and rear ends with the dip, and enable the straps to slide through front and rear openings of the cover, and releasing the latches will cause the sliding plate to fall due to the expanding resilient assembly, and cause the front and rear ends to fall into the dip.
