Disclosed is a buckle device, which locks a resilient band having a plurality of stoppers formed in the lengthwise direction such that the resilient band is unlockable. The buckle device comprises: a buckle holder; and a pair of slide buckles slidably inserted into the buckle holder. The buckle holder includes: a pair of locking pins which are spaced apart from each other and which enable a pair of resilient bands to be caught thereby; and a pair of guide planes inclined in the direction opposite the plane that passes through the pair of locking pins. The slide buckles have ratchet protrusions which are caught by the stoppers of the resilient band, and slide planes to surface-contact the guide planes of the buckle holder.; The slide buckle is movable between an unlocked position, in which the stoppers push the ratchet protrusions in a first direction, to enable the resilient band to move between the ratchet protrusions and the locking pins, and a locked position, in which the stoppers push the ratchet protrusions in a second direction opposite the first direction to enable the ratchet protrusions to press the resilient band against the locking pins.