Buckle and timepiece

A buckle that links a first band and a second band to each other, the buckle comprising:

• a folding member linked to the first band;
• a buckle cover pivotably linked to the folding member;
• a slide plate supported slidably relative to the buckle cover in a longitudinal direction of the first band and the second band and linked to the second band;
• a swing arm rotatably supported by the buckle cover;
• and
• a spring that urges the swing arm,
• wherein the slide plate has a plurality of groove sections provided along the longitudinal direction,
• the swing arm includes an engagement click engageable with any of the groove sections of the slide plate and is supported rotatably in a first rotational direction in which the engagement click engages with any of the groove sections and in a second rotational direction in which the engagement click separates from the groove section,
• the spring urges the swing arm in the first rotational direction, and
• the folding member restricts rotation of the swing arm in the second rotational direction when the folding member is accommodated in the buckle cover, and cancels the restriction of the rotation of the swing arm in the second rotational direction when the folding member is detached from the buckle cover.