To provide an electrode active substrate indicating an excellent battery characteristic such as e.g., electric capacitance or high-rate charging/discharging property.

An electrode active substance is comprised of a mixture of a specific titanium compound having a one-dimensional tunnel structure and a lithium titanium compound having a spinel crystal structure. The electrode active substance is an excellent material indicating a battery characteristic such as e.g., initial capacitance or high-rate charging/discharging capacitance exceeding the battery characteristic in the case of single use as an active substance. Therefore, practical usefulness is improved as a power storage device electrode material of a lithium secondary battery or the like. Furthermore, a manufacturing method thereof does not require any special device, either, and raw materials to be used are also low priced, thereby manufacturing a high value-added material at low costs.