A positive electrode active material includes a primary particle (1), wherein the primary particle (1) contains an olivine-type phosphate compound, the primary particle (1) has a cross-section in at least part of which a streak structure is provided, the streak structure includes a first region (1a) and a second region (1b), the second region (1b) contains an ion conductor containing phosphorus at a higher concentration as compared to the first region (1a), the second region (1b) extends in a streaky manner, and the first region (1a) is divided into two or more by the second region (1b).
