Disclosed is a galvannealed steel sheet having an excellent surface appearance, wherein plating failure and non-uniform alloying are suppressed. Also disclosed is a method for producing such a galvannealed steel sheet. The galvannealed steel sheet is obtained by hot-dip galvanizing a base steel, and then alloying the plating layer. The base steel is obtained by hot rolling a steel which contains 0.02-0.25 mass % of C, 0.5-3 mass % of Si, 1-4 mass % of Mn, 0.03-1 mass % of Cr, not more than 1.5 mass % of Al (excluding 0 mass %), not more than 0.03 mass % of P (excluding 0 mass %), not more than 0.03 mass % of S (excluding 0 mass %) and 0.003-1 mass % Ti, and additionally contains 0.25-5.0 mass % of Cu and 0.05-1.0 mass % of Ni, while satisfying formula (1), with the balance being made up of iron and unavoidable impurities. [Cu]/[Ni]≧5 In formula (1), [ ] represents the content (mass %) of each element.