A surface-coated aluminum and zinc plated steel sheet in accordance with the present invention includes: a plated steel sheet; a composite coating film formed by applying an aqueous surface treatment agent on the plated steel sheet and drying the aqueous surface treatment agent. The aqueous surface treatment agent contains a water dispersible resin (A), a cobalt compound (B), and water, and has a pH within a range of 7.5 to 10. The composite coating film contains the water dispersible resin (A) and the cobalt compound (B). A percentage by mass of the water dispersible resin (A) in the composite coating film is 90% or more. A mass of the composite coating film per one surface of the plated steel sheet falls within a range of 0.5 to 3.5 g/m2.