Nobuko Inagaki, 55, reportedly lost her temper because of sniping by her 83-year-old mother Yuri at the home they shared in Okazaki, central Japan yesterday.
Inagaki junior, who is president of a cotton spinning company, made an emergency call after attacking her mother with the kettle and told officers who arrived at the scene: "I killed my mother", local television reported.
A police spokesman said they were questioning the younger women on suspicion of murder.
In August last year, a 61-year-old housewife from southwest of Tokyo reportedly battered her septuagenarian husband to death with a coffee cup after discovering he was being unfaithful.