Satyakumar of JJ Nagar locality was arrested soon after the incident last night, they said.
He had been employed in Canada earlier and returned home three years ago but remained unemployed since then.
Last night, he suddenly carried his 60-year-old mother, Jyothipraba, out of the house and threw her into a nearby old well, police said, adding neighbours who heard the commotion rushed to the spot and informed them.
Police and Fire and Rescue Services Personnel rescued her and rushed her to a nearby government hospital but she was declared brought dead by doctors, they said.