The crystal structures and magnetic characteristics of the superconducting substance in YBa₂(Cu_1-xM_x)₃O_y, where M is 3 dtransition element and x=0, 0.01, 0.03, 0.10, were investigated. Substitution of Ni and Zn left the orthorhombic structure at x=0.10, whereas substitution of Fe and Co induced an orthorhombic to tetragonal transition at x=0.03. The valency of substituted Co ion was divalence, whereas the valency of other substituted magnetic ions was not determined for certain.