The invention relates to a folding buckle clasp for a strap (2) of a timepiece (3), which can take up a closed position for keeping the strap (2) around the wearer's wrist and an open position for removing the strap (2) from the wearer's hand, the clasp (1) being provided with a flexible locking member (4) comprising ends (5) that are mounted in a pivotable manner with first and second folding leaves (6a, 6b) attached in a hinged manner to first and second strands (7a, 7b), respectively, of the strap (2), said flexible member (4) being defined to keep the first and second leaves (6a, 6b) folded in a locked manner in the closed position of the clasp (1) by having two components (8a, 8b) connected together by an elastic connection (9).