An electrode for a secondary battery comprises a current collector; and an active material-containing layer has active materials which comprise titanium-containing composite oxide having an orthorhombic crystal structure and represented by a general formula Li2+aM12−bTi6−cM2dO14+δ;
wherein the active material-containing layer has intensity ratio Ia/Ib in an X-ray diffraction pattern of the active material-containing layer, the Ia and the Ib are obtained by powder X-ray diffraction method using Cu-Kα ray, the intensity ratio is within a range of 0.5≤Ia/Ib≤2, the Ia is the strongest intensity of a diffraction peak among diffraction peaks appearing within a range of 42°≤2θ≤44°, and the Ib is the strongest intensity of a diffraction peak among diffraction peaks appearing within a range of 44°