New oxide materials for the positive electrode consisting of lithium, iron, titanium, and manganese (Li_1+x(Fe_0.3Mn_0.7)_1-xO₂ and Li_1+x(Fe_0.3Mn₀₅Ti_0.2)_1-xO₂, 0<x<1/3) are developed by a wet chemical method including carbothermal reduction process. These materials do not contain rare metals, cobalt and nickel, and have favorable battery characteristics (about 250 mAh/g of initial discharge capacity and above 80 % of initial cycle efficiency) in the same potential range (2.0-4.8 V) as that of conventional positive electrodes (Li_1.2Co_0.13Ni_0.13Mn_0.54O₂). This development offers a high prospect for conserving resources and reducing the cost of rechargeable lithium-ion batteries used in electric vehicles by utilizing iron and titanium.