The seizure was made during a vehicle check at Gobichettipalayam-Modachur main road last night.
The notes worth Rs 36.9 lakh, were found in a cloth bag in the car and all the five persons in the vehicle were arrested, police said.
The arrested, identified as Sakthivel, Manoj, Suresh Senthilkumar and Sabari, told the police that they were carrying the money to exchange with demonetised notes to some "affluent" persons for a good margin in Gobichettipalayam.
All five persons, their car and the seized currency were handed over to Income Tax Department officials today for questioning, police said.