Provided is a method for manufacturing a flexible metal-clad laminate using a casting method, including: (a) forming a first polyimide layer having a coefficient of linear thermal expansion of 25 ppm/K or less above a metal layer; (b) plasma-treating a surface of the first polyimide layer; and (c) forming a second polyimide layer having a coefficient of linear thermal expansion of 25 ppm/K or lower above the first polyimide layer. The flexible metal-clad laminate according to the present invention can have excellent adhesion between the polymer film and the metal conductive layer, a low dimensional change, and a low production cost, because of superior casting workability, even though the thickness of polyimide becomes increased.