A lithium battery (1) including a positive electrode (10) containing low-crystallinity manganese dioxide having a specific surface area of 8 to 28 m2/g as a positive electrode active material, a negative electrode (11) containing metallic lithium or a lithium alloy as a negative electrode active material, and an organic electrolyte is provided. The lithium battery (1), due to said low-crystallinity manganese dioxide contained therein, has excellent storage characteristics at high temperatures of 100° C. or higher, large-current discharge characteristics, large-current pulse discharge characteristics, low-temperature discharge characteristics, and like characteristics, and in addition, is cost advantageous.