The effect of cold-rolling reduction on texture and planar anisotropy of the r-value was investigated in type 329J4L duplex stainless steel (DSS) sheet, which has a two-phase ferrite (α) and austenite (γ) microstructure. In addition, the possibility of predicting the planar anisotropy of the r-value on the basis of the Taylor theory was investigated in consideration of the texture gradient through the thickness. An increase in cold-rolling reduction resulted in the improved average r-value and the strong directionality with a maximum value at the diagonal direction. The α phase had an extremely strong α_bcc-fiber texture and the γ phase had β- and α_fcc-fiber textures. The texture gradient in the thickness direction was more remarkable in the α phase than in the γ phase. The r-values calculated from the overall texture of the α phase using the relaxed constraints model with two relaxed shear strain constraints e₁₃, e₂₃ and a CRSS ratio of 1.1 for {112} and {011}⟨111⟩ glide systems were in quite good agreement with the experimental r-values. This suggested that slip deformation in the α matrix was dominant for type 329J4L DSS sheet. However, the difference between the experimental and calculated results was remarkable in the vicinity of the diagonal direction.