An aluminum alloy contains at least 0.03 mass % and at most 1.5 mass % of Mg, at least 0.02 mass % and at most 2.0 mass % of Si, and a remainder composed of Al and an inevitable impurity, a mass ratio Mg/Si being not lower than 0.5 and not higher than 3.5. In a transverse section of the aluminum alloy wire, a rectangular surface-layer void measurement region having a short side of 30 μm long and a long side of 50 μm long is taken from a surface-layer region extending by up to 30 μm in a direction of depth from a surface of the aluminum alloy wire. A total cross-sectional area of voids present in the surface-layer void measurement region is not greater than 2 μm2.