Officials said they seized the amount during a vehicle check at Elumathur, 20 km from here.
The passenger, a PWD contractor, said he had drawn the amount from a bank and would submit a receipt for it soon, officials said.
The money was seized and it was deposited in the Treasury, officials added.
Ahead of the May 16 Assembly polls, a strict vigil is being maintained by the Election Commission against transportation of unaccounted money and illegal money transactions.