Prasad was arrested on the dais for an election meeting here, said district superintendent of police Saket Kumar Singh.
The police had lodged an FIR against Prasad and his pilot after his helicopter landed at the venue of an election meeting on April 7 instead of the nearby helipad.
The FIR was lodged by block development officer Subhas Singh.
The Election Commission had served a notice to Prasad for violating the model code.
''The Election Commission issued the notice on Monday and asked him (Lalu Prasad) to reply by 4 pm on Tuesday,'' Assistant Chief Electoral Officer A K Sinha, said.
