In 1563, the former family head Nagamasa IKEDA died, then Katsumasa took over his father's position as the heir of the Ikeda family in Settu Province (He was not a son of Nagamasa but because he was talented both in literary and military arts, he was elected as the heir of the Ikeda family).
永禄6年（1563年）、前当主の池田長正の死去によって摂津池田家惣領として家督を継ぐ（長正の子ではなかったが、文武に秀でていたため池田家当主となる。