To provide a method for manufacturing a ferroelectric film formed of a lead-free material. The method for manufacturing a ferroelectric film according to an aspect of the present invention is a method for manufacturing a ferroelectric film including the steps of pouring a sol-gel solution for forming (K1-XNaX)NbO3 into a mold 3, calcining the sol-gel solution to form a (K1-XNaX)NbO3 material film inside the mold 3, heat-treating and crystallizing the (K1-XNaX)NbO3 material film in an oxygen atmosphere to form a (K1-XNaX)NbO3 crystallized film inside the mold 3 and removing the mold 3 through etching, and is characterized in that the mold 3 is more easily etched than the (K1-XNaX)NbO3 crystallized film and the X satisfies a formula below 0.3≦X≦0.7.