Additional Chief Electoral Officer R Lakshmanan told reporters that the person, who was riding a bike, was stopped and searched after which Rs 10 lakh was seized from him.
The police and I-T personnel are interrogating him to gather details about the cash seized in Nalanda, he said.
Nalanda is the native district of Chief Minister Nitish Kumar.
This was the second big seizure of cash in the state after the city police intercepted a vehicle carrying currency notes worth Rs 25 lakh last week.
SSB DIG Deepak Kumar said, "We have increased patrolling on the Indo-Nepal border to check movement of Maoists, criminals, weapons and fake currency notes. It will be intensified as election dates come closer."
On the other hand, the Bihar excise department conducted 1,634 raids across the state and arrested 977 persons with illicit and unaccounted liquor allegedly to be used to influence voters. Rs 23.16 lakh has been collected in fines from them.
