The invention discloses a compound having an olivine-type structure, which enables to produce a battery having high capacity, high output and excellent rate characteristics. Also disclosed are a positive electrode for nonaqueous electrolyte secondary batteries, which is produced by using such a compound, and a nonaqueous electrolyte secondary battery comprising such a positive electrode. Specifically disclosed is a compound containing at least lithium, a transition metal, phosphorus and oxygen, such as LiFePO4. The compound has an olivine-type structure and hardly contains a crystal phase other than one with olivine-type structure, while having a specific surface area of not less than 4 m<2>/g. This compound is useful as a positive electrode active material for nonaqueous electrolyte secondary batteries.