A lithium primary battery 10 includes an electrode group in which a positive electrode 1 having iron disulfide as a positive electrode active material and a negative electrode 2 having lithium as a negative electrode active material are wound, with a separator 3 interposed between the positive electrode 1 and the negative electrode, wherein a density of the iron disulfide in a positive electrode mixture containing the positive electrode active material is in a range of 2.2-2.9 g/cm3, and the separator 3 is made of a non-woven fabric whose tensile strength is in a range of 6-30 N/mm2.