To provide a method for manufacturing retardation films capable of suppressing fracture in handling in drawing a film or after the drawing and stably and continuously satisfying a relation of 0.92≤R₄₀/Re≤1.08.

A drawing step includes: a first drawing step of performing a uniaxial drawing process for a specific film before the drawing in one direction, the specific film before the drawing including a resin layer a1 containing polycarbonate, a resin layer b containing resin B having a negative intrinsic birefringence, and a resin layer a2 containing polycarbonate; and a second drawing step of performing a uniaxial drawing process in the direction orthogonal to the direction in which the uniaxial drawing step is performed in the first drawing step. A plane orientation coefficient represented by (nx+ny)/2-nz of a resin layer A1 and a resin layer A2 formed by drawing the resin layer a1 and the resin layer a2 by the drawing step respectively is defined to 0.017 or more.