To provide a method for correcting a curl generated in a composite foil without rendering a damage such as contamination with oil and scratches, and a composite foil the curl of which is corrected.

In order to solve the above problem, the composite foil having a curl of not greater than 10 mm after heating is obtained by applying a method for correcting a curl of a composite foil that the composite foil is heated at an ambient temperature of 120°C-250°C for 1 hr-10 hr, preferably at 150°C-200°C for 1 hr-7 hr. The method is particularly effective for an extremely thin electrolytic copper foil with a carrier copper foil as a composite foil to be corrected.