POSITIVE ELECTRODE ACTIVE MATERIAL AND LITHIUM SECONDARY BATTERY

There is provided a positive electrode active material having a specific surface area of 0.1 to 0.5 m 2 /g, which contains a large number of crystal grains containing primary particles of 5 to 20 µm in particle diameter, composed of lithium manganate of spinel structure containing lithium and manganese as the constituent elements, and a bismuth compound containing bismuth. The proportion of the primary particles contained in the large number of crystal grains is 70 areal % or more and the proportion of the bismuth contained in the bismuth compound is 0.005 to 0.5 mol % relative to the manganese contained in the lithium manganate.