An Al—Si—Mg aluminum alloy is provided. The Al—Si—Mg aluminum alloy includes: 5 mass % or larger and 10 mass % or smaller of Si; 0.2 mass % or larger and 1.0 mass% or smaller of Mg, 0.03 mass % or larger and 0.5 mass % or smaller of Sb; 0.0004 mass % or larger and 0.0026 mass % or smaller of Be; and a remainder having an alloy composition including Al and unavoidable impurities. In L*a*b* color system, a value of L* that indicates lightness of a surface thereof is 55 or larger.