Austfjorden is a fjord in the south of Masfjorden in Hordaland, Norway. It has a length of about 20 kilometres (12 mi) and extends south-east.
On the north side of the east area there are several deep bays. The first of these is the 2-kilometre (1 mi) long Mjangersvågen with Mjanger the bottom. The next two are Nordkvingevågen harbor into Nordkvingo and Sørekvingevågen harbor into Sørkvingo. Between these two lies the cape Melshovden. A little further into the fjord is Kjekallevågen where there is a causeway and a bridge, the outermost of the bay along the County Road 374 west of Kjekallevågen. From here, Austefjorden stretches 6 kilometres (4 mi) farther southeast, while Hidnesfjorden goes a further 2 kilometres (1 mi).