The present invention provides an Al alloy thin film for a semiconductor device electrode having an electrical resistivity of as low as 6 .mu..OMEGA.cm or less, high hillock resistance, high void resistance, and high corrosion resistance against an alkaline solution, which are required for an electrode thin film of large-screen liquid crystal display (LCD) or high-resolution LCD. The present invention also provides a sputtering target to deposit the Al alloy film by sputtering process for a semiconductor device electrode. The Al alloy thin film for a semiconductor device electrode satisfies the conditions of Y.gtoreq.0.3 at %, IVa group metal element.gtoreq.0.2 at %, and 0.3C.sub.y +3C.sub.IVa.ltoreq.2 (wherein C.sub.y : Y content (at %), C.sub.IVa : content of IVa group metal element (at %)), and the sputtering target is made of an Al alloy satisfying the above conditions.