The invention relates to a fixer, in particular to a water cup fixer. The water cup fixer cannot increase the loads on a human body and cannot restrain people from controlling a motorcycle in the riding process. By means of the technical scheme, the water cup fixer comprises a placement bucket, a fixing device, first guide sleeves, first guide rods, a first rack, clamping blocks, a first gear, a second rack, a third rack, a second gear and the like. The fixing device is arranged in the middle of the left side of the placement bucket. A slot is formed in the lower portion in the placement bucket and communicates with the interior of the placement bucket. The left side and the right side of the rear wall of the slot are provided with the first guide sleeves correspondingly. The first guide rods are slidingly arranged in the first guide sleeves. By hanging the placement bucket on a handlebar of the motorcycle through the fixing device, people can conveniently place a water cup in the riding process; and by swinging a thumbing clamping rod up and down to adjust the distance between the left and right square clamping blocks, the water cup can be fixed by the left and right square clamping blocks.