Abstract Anisotropic magnetic-field dependence of the critical current density (J c) of polycrystalline YBa 2Cu 3O 7−δ thin films deposited on (100)MgO. (100)SrTiO 3 and a-axis oriented BaSnO 3 was studied. For the films on MgO 2. J c changes from J c(B//substrate surface)≈1×10 5 A/cm 2 to J c(B⊥ substrate surface)≈4×10 4 A/cm 2 at 77.3K and 0.6T. On the other hand, for the films on SrTiO 3, J c is almost constant at about J c(B//)≅J c(B⊥)≈3×10 5 A/cm 2 under the same conditions. Transmission electron microscopy shows that the films on MgO consist of c-axis oriented small YBa 2Cu 3O 7−δ grains (∼ 1 μm in size), while the films on SrTiO 3 consist of a mixture of a-axis and c-axis oriented small YBa 2Cu 3O 7−δ grains (∼0.5μm in size). These facts suggest that the dependence of J c on the direction of the applied magnetic field strongly reflect the microstructure of the thin films.