The influence of Ni substituted for Cu in YBa2Cu3O7−δ on the intra‐ and intergrain properties is studied. All intragrain critical parameters are gradually degraded with increasing concentration x of nickel. On the contrary, the intergrain critical current at H = 0 A/m is the same for all x in the concentration regime 0 ≦ x ≦ 0.09. It is, therefore, concluded that the amount of impurity phases or defects incorporating nickel increases with x and locates mainly inside grains, deteriorating the intragrain critical parameters.