The present invention provides a very lightweight magnesium-lithium alloy which has both corrosion resistance and cold workability balanced at high levels, a certain degree of tensile strength, low surface electrical resistivity, as well as a rolled material and a formed article made of the alloy, and a method of producing the alloy, by means of a magnesium-lithium alloy containing not less than 10.5 mass % and not more than 16.0 mass % Li, not less than 0.50 mass % and not more than 1.50 mass % Al, and the balance of Mg, and having an average crystal grain size of not smaller than 5 μm and not larger than 40 μm, a tensile strength of not lower than 150 MPa, and a surface electrical resistivity of not higher than 1Ω as measured with an ammeter by pressing a cylindrical two-point probe with a pin-to-pin spacing of 10 mm and a pin tip diameter of 2 mm (contact surface area of one pin is 3.14 mm2), against an alloy surface at a load of 240 g.