BUCKLE

PROBLEM TO BE SOLVED: To provide a buckle including a male member and a female member detachable from each other, configured to control the insertion direction of the male member in a lateral direction facing the female member, and to guide the male member to a slot of the female member while centering the male member.SOLUTION: In a buckle 10, an insertion part 50 provided in a male member 30 is inserted and engaged into a slot 71 of a female member 40. The female member has a tongue piece 93 extending in the insertion direction of the male member from the slot. The tongue piece is provided in one inner wall (e.g. a bottom wall 91) of a pair of facing inner walls of the female member, and has a guide groove formed at least on the one inner wall (e.g. the bottom wall) for guiding a guide projection 53 provided in the male member.