A coil material capable of contributing to an improvement of the productivity of a high-strength magnesium alloy sheet and a method for manufacturing the coil material are provided. Regarding the method for manufacturing a coil material through coiling of a sheet material formed from a metal into the shape of a cylinder, so as to produce the coil material, the sheet material is a cast material of a magnesium alloy discharged from a continuous casting machine and the thickness t (mm) thereof is 7 mm or less. The sheet material 1 is coiled with a coiler while the temperature T (° C.) of the sheet material 1 just before coiling is controlled to be a temperature at which the surface strain ((t/R)×100) represented by the thickness t and the bending radius R (mm) of the sheet material 1 becomes less than or equal to the elongation at room temperature of the sheet material 1.