A buckle includes a male member and a female member. The male member includes: a base to which a string member is attachable; a pair of legs that project from the base and are elastically deformable in directions intersecting an insertion direction of the male member; and engaging portions that are provided to the legs and are engageable with the female member. When the male member is inserted into the female member, parts of the legs come into contact with inner walls of the female member to form biasing portions that bias the male member in an opposite-insertion direction using a resilience of the legs.