The Palamau administration issued the ban order after leaders of the 80,000 para teachers on strike since November 15 demanding regularization of their service vowed to show black flags to Modi in Palamau.
"The government staff or common people cannot wear black socks," an official said. "The ban also covers clothes, bags, shoes, purses and caps."
Modi is scheduled to arrive in Palamau at 10.30 a.m. to spend an hour in the district.
The Prime Minister will lay the foundation stone of the Mandal dam irrigation project, which was pending since 1972. The dam will be built at a cost of Rs 2,500 crore.
He will also lay the foundation stone of a pipeline to meet the needs of drinking water and irrigation in Palamu and Garhwa districts at a cost of Rs 1,138 crore.