There is provided a bottom periphery length adjustment mechanism usable for apparel in which a very high importance is attached to design of appearance. The length adjustment mechanism comprises a slide adjuster. The slide adjuster comprises a band and a buckle that are formed of a synthetic resin. An engagement claw of the buckle is engaged with a serrated engagement groove provided on the outer surface of the band so that, in an engaged state, the band freely approaches the buckle but cannot retract. The buckle is fixed to the backside of the bottom. When the band approaches the buckle, the periphery of the bottom shrinks while, when the band moves away from the buckle, the periphery of the bottom expands.