Active material particles are provided that exhibit performance suitable for increasing the output of a lithium secondary battery and little deterioration due to charge-discharge cycling. The active material particles provided by the present invention have a hollow structure having secondary particles including an aggregate of a plurality of primary particles of a lithium transition metal oxide, and a hollow portion formed inside the secondary particles, and through holes that penetrates to the hollow portion from the outside are formed in the secondary particles. BET specific surface area of the active material particles is 0.5 to 1.9 m2/g.