Police said the woman was returning home in Balabandh village, about 25 km from here, from the market at around 10.30 am when she was surrounded by hundreds of villagers armed with sticks who beat her to death.
The villagers, the police said, alleged that the woman was practicing sorcery that had led to her brother-in-law being ill.
Superintendent of Police S W Reza said that on receiving information about the matter the police reached the spot and arrested 31 of the named accused.
The police complaint has been filed by the woman's son, he said adding that the 31 arrested include 29 women.
All of them were produced before a local court which remanded them to police custody for 14 days.