A computer enclosure includes a chassis (10), a drive bracket (20) pivotably attached to the chassis, a holder (40) mounted in the chassis, and a positioning member (30) attached to the drive bracket. The holder includes a first clamp (45) with a first groove (451) defined therein. The positioning member includes a first positioning piece (33) corresponding to the first clamp. When the drive bracket is pivoted on the chassis, the first positioning piece is interferentially intruded in the first groove of the first clamp to adjustably position the drive bracket.