The invention relates to a belt retention guide for retaining the position of a belt having beads along its peripheral edge. The belt retention guide comprises a first roller, a movable portion, and a fixing portion. The first roller engages with the beads and retains the position of the beads. The movable portion supports the first roller and the fixing portion engages with the movable portion. The beads are pinched between the first roller and the fixing portion, thereby retaining the position of the belt. The movable portion is configured to be movable between a fixed position where the first roller engages with the beads to pinch them, and a released position where the first roller is separated from the beads to release them. The movable portion is secured in the fixed position by insertion of a stop member through or between the movable portion and the fixing portion.