Arbach is a river in Bavaria, Germany. It is a right tributary of the Swabian Rezat near Pleinfeld in the Middle Franconian district Weißenburg-Gunzenhausen.

The Arbach rises at an altitude of 462 m (1,516 ft) above sea level at Walting in Pleinfeld and feeds there the pond Bachweiher. To the north-east of the wood field sector Totenleite, it is fed on its right side by the Arbachgraben, which is coming from the north from Kreisstraße WUG 16 . It flows further north along the Celtic Viereckschanze and then south of the hill Weingartner Berg (467 m (1,532 ft) above sea level) and finally flows at a height of 373 m (1,224 ft) above sea level in Pleinfeld, north of the street Zollgasse, from the right into the Swabian Rezat.

• List of rivers of Bavaria